1M8 


■ 


;:  Jpr 


it'.IHI' 


W\t  -0.  p.  J!tU  phrarg 


•»♦• 


QH506 
fif>7 


N.C.  STATE  UNIVERSITY     D.H.  HILL  LIBRARY 


S00366687 


Date  Due 


•- 


Feb23'34 


L 


Wf 


19Ar>J1C 


~ 


\ 


FEB  1 


7  1QA? 


MAY 


vm 


19750 


«ne  as  ?&5  l^RLZZ^ 


200M/06-99-991212 


Elms  at  the  Water's  Brink. 


PRACTICAL  BIOLOGY 


BY 

W.    M.    SMALLWOOD 

SYRACUSE   UNIVERSITY 

IDA    L.    REVELEY 

WELLS   COLLEGE 

GUY   A.    BAILEY 

GENESEO    STATE    NORMAL   SCHOOL 


-oojojoc- 


ALLYN   AND    BACON 

Boston  Neto  gork  Chicago 


COPYRIGHT,   1916,  BY 

W.    M.    SMALLWOOD,   IDA   L.    REVELEY 

AND   GUY   A.    BAILEY 


ADR 


Notijjooli  UJregg 

J.  S.  Cushing  Co.  —  Berwick  &  Smith  Co. 

Norwood,  Mass.,  U.S.A. 


( 

PREFACE 

Practical  Biology  offers  a  simple,  workable,  attractive, 
flexible,  and  teachable  course  in  Biology. 

Simplicity  is  a  feature  of  the  book.  The  language  is  simple, 
not  technical,  and  the  style  is  easy,  flowing,  and  colloquial. 
The  pupil  is  assisted  by  many  mechanical  helps.  Small  cuts 
or  larger  pictures  illustrate  each  new  topic  and  there  are  many 
charts  and  maps. 

The  practical  aspects  of  Biology  are  emphasized.  A  study 
is  made  of  the  economic  value  of  plants  and  animals,  and  of 
the  characteristics  which  make  them  beneficial  or  harmful  to 
mankind.  * 

The  attractive  illustrations,  many  of  which  were  made  es- 
pecially for  the  book,  are  a  feature  of  the  Biology.  In  addi- 
tion to  the  cuts  and  pictures  which  illustrate  the  text,  there 
are  portraits  of  the  leading  biologists  of  the  world,  with  brief 
accounts  of  their  lives  and  of  their  contributions  to  the  subject. 

The  flexibility  of  the  book  enables  teachers  to  begin  with 
the  study  of  animals  or  with  the  study  of  plants. 

A  number  of  features  help  to  make  Practical  Biology  teach- 
able, (a)  The  paragraphs  are  short,  and  there  are  summaries 
and  questions  at  the  end  of  each  chapter,  (b)  Well-known 
types  like  the  grasshopper  and  the  bean  plant  are  studied  first, 
and  the  treatment  passes  from  the  known  to  the  unknown, 
(c)  The  pronunciation  and  derivation  of  technical  names  are 
given  in  the  text  the  first  time  the  names  occur,  (cl)  There  is 
an  introduction  defining  the  common  scientific  terms  used  in 
the  study  of  Biology,  (e)  Optional  field  work  and  students' 
reports  are  provided  for.     (/)  Laboratory  work  is  contained 

iii 


iv  PREFACE 

in  the  book,  so  that  a  special  manual  is  unnecessary,  (g)  The 
index  is  unusually  complete. 

The  treatment  of  human  biology  emphasizes  hygiene  and 
sanitation  and  contains  graphic  diagrams  illustrating  the  sec- 
tions on  health  and  disease.  This  treatment  will  be  found 
especially  practical.  The  treatment  of  alcohol  and  narcotics 
is  adequate,  but  sane. 

For  teachers  in  New  York  State  a  feature  of  the  book  is  its 
close  relation  to  the  Regents'  Syllabus,  which  it  covers  exactly. 
It  is  equally  suited  to  courses  laid  down  for  various  other 
states,  notably  Massachusetts  and  Ohio. 

The  book  has  a  number  of  appendices,  one  of  which  has 
to  do  with  bird  study.  Another  contains  the  sanitary  code  of 
the  State  of  New  York. 

The  work  is  so  arranged  that  the  course,  though  simple,  is 
thoroughly  scientific.  Science  is  organized  knowledge,  and 
the  simple  student  reports  in  the  form  of  tables  lead  the  pupil 
to  make  a  correct  and  logical  classification  of  his  facts,  thus 
laying  the  foundation  for  scientific  study. 

W.  M.  S. 
I.  L.  R. 
G.  A.  B. 
July,  1916. 


ACKNOWLEDGMENT   OF   ILLUSTRATIONS 

Guy  A.  Bailey,  Bird  and  Mammal  Photographs  (in  nature). 
Fred  Baker,  New  York  State  College  of  Forestry,  406. 
Hugh  P.  Baker,  New  York  State  College  of  Forestry,  411,  414. 
M.  W.  Blackmail,  New  York  State  College  of  Forestry,  2,  127, 

128. 
S.  S.  Berry,  100. 

G.  Sidney  Britton,  Syracuse,  N.  Y.,  145,  146. 
W.  E.  Britton,  Connecticut,  Agriculture  Station,  27. 
W.  Coe,  Yale  University,  73,  74. 
Conservation  Commission,  N.  Y.  State,  412,  413,  415,  416,  417, 

418,  419,  420. 
Hugh  Findlay,  College  of  Agriculture,  Syracuse    University, 

17,  18,  308,  330,  348,  355,  357,  358,  359,  362,  435,  436,  437. 
Hugh  Findlay  and  Dr.  I.  H.  Levy,  346,  441. 
Fitzhenry-Guptill  Co.,  Boston,  16. 
Geneva  Experimental  Station,  N.  Y.,  383,  384,  385. 
Illinois  State  Laboratory  of  Natural  History,  430,  431. 
J.  E.  Kirkwood,  University  Montana,  1. 
Dr.  J.  S.  Marshall,  Berkeley,  Cal.,  182,  183. 
D.  F.  MacDougal,  Desert  Laboratory,  Tucson,  Arizona,  432. 
S.  O.  Mast,  Johns  Hopkins  University,  49. 
N.  Y.  State  Bureau  of  Health,  238,  242,  243,  244,  245. 
Dr.  Edward  Packard,  Saranac  Lake,  N.  Y.,  239,  240. 
Parrott  and  Fulmer,  Geneva  Experimental  Station,  N.  Y.,  10. 
F.  C.  Paulmier,  Albany,  N.  Y.,  87,  88. 

Dr.  C.  Potter,  Syracuse,  N.  Y ,  185,  186,  195, 196,  197,  198,  199. 
L.  Pennington,  New  York  State  College  of  Forestry,  Syracu^  . 

N.  Y.,  380,  381,  382. 

v 


VI  ACKNOWLEDGMENT  OF  ILLUSTRATIONS 

A.  M.  Reese,  University  West  Virginia,  Morgantown,  W.  Va., 
133,  134. 

A.  G.  Rutheven,  University  Michigan,  Ann  Arbor,  131,  132. 
G.  B.  Simpson,  Albany,  N.  Y.,  14,  93,  94,  95. 

B.  G.  Smith,  Ypsilanti,  Michigan,  113. 

W.  H.  Snyder,  Los  Angeles,  42,  123,  135,  159,  167,  176,  177, 

222,  241,  280,  433,  440. 
Syracuse  Universit}^,  Agricultural  College,  246,  247. 
Crystal  Thompson,  Ann  Arbor,  Michigan,  114. 
J.  M.  Thorburn  &  Co.,  New  York  City,  220,  278,  279,  297,  298, 

329,  361,  378. 

C.  H.  Townsend,  N.  Y.  Aquarium,  105,  106,  107,  108. 
U.  S.  Census  1910,  248,  340,  343,  344,  352,  356. 

U.  S.  Department  of  Agriculture,  7,  9,  11,  12,  13,  19,  33,  34, 
35,  37,  38,  39,  43,  44,  56,  85,  96,  102,  103,  111,  112,  171, 
172,  173,  269,  270,  290,  293,  294,  295,  315, 337,  345,  349. 

Jerome  Walker,  Physiology,  213,  220, 221. 

Anti-Saloon  League,  230,  231,  232,  234. 


TABLE   OF   CONTENTS 

PART   I 
ANIMAL   BIOLOGY 

PAGE 

Introduction 1 

CHAPTER 

I.     The  Grasshopper.     A  Representative  Animal         .         .         .11 

II.     Other  Common  Insects 24 

III.  The  Simplest  Animals — Protozoa 45 

IV.  The  Simpler  Metazoa 55 

V.     Ccelenterates,  Hydra-like  Animals 63 

VI.     The  Starfish  Family.     (Optional) 71 

VII.     The  Worm  Group 76 

VIII.     Crustaceans  and  Related  Forms 86 

IX.     The  Mollusks 94 

X.     Fishes 103 

XI.     Amphibians 113 

XII.     Reptiles 129 

XIII.  Birds 136 

XIV.  Mammals 150 


PART    II 

HUMAN   BIOLOGY 

XV.  Life  Processes  of  Man 161 

XVI.  The  Skeleton  and  Muscles       .         .         .         .         .         .         .184 

XVII.  Respiration,  Blood,  and  Excretion 192 

XVIII.  The  Nervous  System  of  Man  .  ...     209 

XIX.  The  Biology  of  Disease  ....  ...    232 

19722 


vm 


TABLE   OF   CONTENTS 


PART    III 


PLANT   BIOLOGY 

CHAPTEE  PAGE 

XX.     Typical  Flowering  Plants     .......  259 

XXI.     Other  Flowering  Plants 323 

XXII.     The  Simplest  Plants 338 

XXIII.  The  Smallest  Plants  (Bacteria)    ......  343 

XXIV.  Fungi 354 

XXV.     Mosses  and  Their  Allies 364 

XXVI.     Ferns  and  Their  Allies 369 

XXVII.     The  Conifers  (Gymnosperms) 376 

XXVIII.     Peculiarities  of  Plant  Life     .......  389 

Appendix  A 405 

Bird  Study. 

Appendix  B 408 

Sanitary  Code  of  New  York. 

Appendix  C  ......         <>         ...»  414 

Cancer. 


LIST   OF   ILLUSTRATIONS 

Elms  at  the  Water's  Brink Frontispiece 

FIGURE  PAGE 

1.  Simple  Osmometer 3 

2.  Plant  Cell 4 

3.  Animal  Cell 4 

4.  Tissue     ............  5 

5.  Diagram :    Showing  proportion  of  chemical   elements  in   living 

things 8 

6.  Female  Grasshopper 11 

7.  Diagram  :  Showing  main  parts  of  the  grasshopper        ...  13 

8.  Mouth  Parts  of  the  Grasshopper     .         .         .         .         .         .         .14 

9.  Grasshopper  Laying  Eggs      .         .         .         .         .         .         .         .15 

10.  Incomplete  Metamorphosis  of  the  Tree  Cricket     ....  17 

11.  Codling  Moth  Larva 17 

12.  The  Worm  in  the  Apple 18 

13.  Codling  Moth  Pupa        . 18 

14.  Codling  Moth 19 

15.  Monarch  Butterfly 20 

16.  Modern  Spraying  Outfit                   21 

17.  Plant  Lice  on  Fern 24 

18.  Mealy  Bug 25 

19.  Cicada,  Adult  and  Nymph 25 

20.  May  Beetle 26 

21.  Eggs  of  Ladybug    ........  26 

22.  Holes  Made  by  Woodpeckers         ......  27 

23.  Redheaded  Woodpecker 28 

24.  Larva  of  Mourning  Cloak  Moth 28 

25.  Transformation  of  Pupa  of  Mourning  Cloak  Moth  into  Adult        .  29 

26.  Cecropia  Moth 30 

27.  Young  Tobacco  Worm  .                                                     ...  30 

28.  Larvae  of  a  Leaf  Miner •         •         .31 

29.  Cedar  Bird 

30.  A  Geometrid  Moth  .....  .  .32 

31.  Protective  Coloration 33 

32.  Yellow  Swallowtail         .                  33 

ix 


X  LIST   OF   ILLUSTRATIONS 

FIGURE  PAGE 

33.  Honey  Bee  :  Worker  ;  Queen  ;  Drone 34 

34.  Queen  Cell 35 

35.  Honey  Bee  Egg  ;  Young  Larva;  Old  Larva ;   Pupa      ...  35 

36.  Honey  Bees  Clustering  at  Swarming  Time 36 

37.  Capturing  a  Swarm 37 

38.  Model  Apiary 38 

39.  Cutting  Combs  from  Box  Hive 39 

40.  Ichneumon  Flies 40 

41.  Adult  Horn-Tailed  Saw-Fly 40 

42.  Common  Housefly 41 

43.  Eggs  and  Larvae  of  Culex 42 

44.  Adult  Culex  ;  Adult  Anopheles 42 

45.  Microphotograph  of  an  Amoeba     .......  47 

46.  Diagram  of  an  Amoeba 48 

47.  Amoeba  Reproducing  by  Fission .49 

48.  Diagram  of  Paramoecium 50 

49.  Paramoecium 51 

50.  Paramoecium  Reproducing  by  Fission 51 

51.  Vorticella 52 

52.  One  of  the  Foraminfera          .                  52 

53.  Some  Flagellate  Protozoa 52 

54.  Gonium  .         .         .         .         .         .         .         .         ...         .55 

55.  Volvox 56 

56.  Bath  Sponge 58 

57.  Diagram  :  Showing  parts  of  sponge       ......  59 

58.  Spicules  of  Lime 59 

59.  Two  Stages  in  the  Development  of  the  Sponge  60 

60.  Microphotographs  of  Hydra 63 

61.  Diagram  of  Body  of  Hydra    . 64 

62.  Microphotograph  of  Body  Wall  of  Hydra 64 

63.  Diagram  of  Cell  Layers          ........  65 

64.  Microphotograph  of  the  Hydroid  Obelia 66 

65.  Diagram  of  the  Hydroid  Bougainvillea  66 

66.  A  Hydroid  Colony  that  Looks  Like  a  Plant  67 

67.  A  Hydroid  Medusa 67 

68.  The  Medusa  Known  as  Pelagia '67 

69.  Pennaria  Tiarella  . 68 

70.  Some  Common  Corals  . 69 

71.  Starfish 71 

72.  Diagram  of  Body  of  Starfish 72 

73.  Anatomy  of  the  Starfish 72 

74.  Purple  Sea  Urchin 74 


LIST  OF  ILLUSTRATIONS  XI 

FIGURE  PAGE 

75.  Sea  Lily      .      ,  .                           74 

76.  A  Planarian  Worm 77 

77.  Trichinella 78 

78.  A  Common  Tapeworm        ........  78 

79.  Hair  Worm  in  the  Body  of  a  Grasshopper          ....  79 

80.  Diagram  of  the  Organs  of  Earthworm  from  the  Side          .         .  81 

81.  Earthworm           . 82 

82.  Dero 84 

83.  Crayfish  Bearing  Eggs        ........  86 

84.  Crayfish      .  '      .                           87 

85.  Molted  Exoskeleton  of  Lobster 87 

86.  Organs  of  Crayfish 89 

87.  Soft-Shell  Crab 91 

88.  Pill  Bug .  91 

89.  Cyclops       .         .                 ....                 ...  91 

90.  Daddy-Long-Legs       .....                  ...  92 

91.  Spider 92 

92.  Thousand-legged  Worm  ;  Centipede           .....  92 

93.  Clam ;  Showing  Foot 94 

94.  Right  Shell  of  Clam 95 

95.  Digestive  Tube  of  Clam 95 

96.  Embryo  of  Clam 97 

97.  Snail 98 

98.  Tongue  of  Snail 98 

99.  Snail  Shells 99 

100.  An  Octopus 99 

101.  Soft-Shell  Clam 100 

102.  Stages  in  Life  History  of  Oyster 101 

103.  Barnacles  and  Clams  Growing  on  Oysters  .         .         .         .101 

104.  Skeleton  of  Fish          . 103 

105.  Perch 104 

106.  Sunfish,  or  Pumpkin  Seed .104 

107.  Catfish,  Bullhead,  or  Horned  Pout     .         .         .         .         .         .105 

108.  Brook  Trout 106 

109.  Scales  of  Fishes  .         .         .         .         ■ 107 

110.  Eggs  of  Land-Locked  Salmon 110 

111.  Young  Fish  ;  Showing  Yolk  Sac .111 

112.  Young  Fish  Fry Ill 

113.  Some  Common  Salamanders 113 

114.  Common  Frog 114 

115.  Diagram  to  Show  Organs  of  Frog 116 

116.  Kidneys  of  the  Frog   ....  .  .117 


Xll  LIST  OF  ILLUSTRATIONS 

FIGURE  PAGE 

117.  Central  Nervous  System  of  Frog          .                           ...  118 

118.  Frog  Eggs :         ...  121 

119.  Diagram  Illustrating  Fertilization  in  Frog  Egg    .         .         .         .121 

120.  Dividing  Egg  of  Frog 122 

121.  Dividing  Egg  Becoming  a  Tadpole 122 

122.  Two  Stages  in  the  Development  of  Tadpoles       ....  123 

123.  Fossil  Shells  of  Animals  Now  Extinct 124 

124.  Tree  Frog 126 

125.  A  Sea  Turtle 129 

126.  Horned  Toad,  a  Lizard 129 

127.  Bull  Snake  with  Hen's  Egg  in  Mouth 130 

128.  Bull  Snake  after  Swallowing  Egg 130 

129.  Head  of  Rattlesnake 131 

130.  Rattles  of  Rattlesnake 131 

131.  Rattlesnake  —  Poisonous 132 

132.  Garter  Snake — Harmless 133 

133.  Eight-Foot  Florida  Alligator         .......  133 

134.  Alligator  Nest 134 

135.  Poisonous  Lizards  ;   the  Gila  Monster 135 

136.  Grebe  .         .         ...         .         • 136 

137.  Herring  Gulls 137 

138.  Adult  Screech  Owl 138 

139.  Skeleton  of  Mallard  Duck .138 

140.  Different  Kinds  of  Birds'  Feet      .......  139 

141.  Loggerhead  Shrike 139 

142.  Young  of  Red-Tailed  Hawk — Beneficial    .....  140 

143.  Head  of  Young  Eagle 140 

144.  The  Robin 141 

145.  Nest  of  Yellow  Warbler 142 

146.  Nest  of  Bittern 142 

147.  Mourning  Dove .         .143 

148.  Chimney  Swift  and  Nest „  144 

149.  Junco .  144 

150.  Female  Bobolink 145 

151.  King  Bird .  145 

152.  Young  Crows  in  Nest 146 

153.  Kingfisher 146 

154.  Hairy  Woodpecker  Eating  Suet 147 

155.  Male  and  Female  Cowbirds 147 

156.  Plan  for  Bird  House 148 

157.  Plan  for  Bird  House .148 

158.  Skeleton  of  Dog .  150 


LIST  OF  ILLUSTRATIONS 


Xlll 


KIGl'RE 


Leaving  Its  Nest 


Deer 


159.  Coyote 

160.  Gray  Squirrel 

161.  Young  Gray  Squirrel 

162.  Young  Foxes 

163.  Bat  Hibernating 

164.  Brown  Bat 

165.  Flying  Squirrel    . 

166.  Deer  Mouse 

167.  Sea  Lions    . 

168.  Stomach  of  Sheep 

169.  Skunk 

170.  Young  Rabbits    . 

171.  Elk      . 
1  72.    Virginia  Deer 

173.  Fawns  of  the  Virginia 

174.  Coon    . 

175.  Young  Woodchucks 

176.  Camel ;  the  Ship  of  the  Desert 

177.  Buffalo         .... 

178.  Alimentary  Canal  of  Frog  . 

179.  Alimentary  Canal  of  Man  . 

180.  Tongue        .... 

181.  Taste  Cells 

182.  Milk  Teeth 

183.  Permanent  Teeth 

184.  Pear-Shaped  Human  Stomach 

185.  X-Ray  Photograph  of  Human  Stomach 

186.  X-Ray  Photograph  of  Appendix  and  Part  o 

187.  Gastric  Gland      ..... 

188.  Microphotograph  of  Stomach 

189.  Diagram  of  Villus        .... 

190.  Home-Made  Apparatus  to  Show  Osmosis 

191.  Skeleton 

192.  Microphotograph  of  Bone   . 

193.  Diagram  of  Bone  Structure 

194.  Cartilage 

195.  X-Ray  of  a  Normal  and  a  Broken  Elbow 

196.  X-Ray  of  Hand  of  Child      . 

197.  X-Ray  of  Hand  of  Adult      . 

198.  Broken  Femur    ..... 

199.  Same  Bone  Ten  Weeks  Later     . 

200.  Muscles  of  Upper  Leg 


f  Large  In 


testine 


PAGE 

150 
151 
151 
151 
151 
152 
152 
153 
153 
154 
154 
154 
155 
156 
156 
157 
157 
158 
158 
163 
165 
165 
165 
166 
167 
168 
168 
169 
169 
170 
174 
175 
184 
185 
185 
185 
185 
186 
186 
187 
187 
188 


XIV 


LIST  OF  ILLUSTRATIONS 


FIGURE 

201.  Voluntary  Muscle  Cells 

202.  Involuntary  Muscle  Cells     . 

203.  Heart  Muscle  Cells      .... 

204.  Various  Forms  of  Cells  in  Human  Body 

205.  Diagram  of  Skin  .... 

206.  Lungs  and  Heart  .... 

207.  Voice  Box,  or  Larynx 

208.  Diagram  of  the  Diaphragm 

209.  Hot-Air  Heating  .... 

210.  Steam  Heating 

211.  Microphotograph  of  Blood  of  Frog 

212.  Diagram  of  Work  of  the  Capillaries     . 

213.  Organs  of  Circulation 

214.  Heart 

215.  Diagram  of  Vein  .... 

216.  Diagram  of  Capillaries 

217.  Main  Arteries  of  Frog 

218.  Main  Arteries  of  Man 

219.  Superficial- Lymphatics  of  Arm  and  Hand 

220.  Section  of  Kidney         .... 

221.  Diagram  showing  Artery,  Vein,  and  Kidney  Tube 

222.  Nervous  System  of  Man 

223.  Nerve  Cells 

224.  Nerve  Cells 

225.  Microphotograph  of  Brain    . 

226.  Diagram  to  show  Reflex  Action 

227.  Section  of  Eye     .... 

228.  How  We  See  the  Pencil 

229.  Plan  of  Ear 

230.  Statistics  :   Skill  and  Endurance  Impaired  by  Drink 

231.  Statistics:   Drink  Impaired  Scholarship 

232.  Statistics  :  Assaults  and  Drink    . 

233.  Brain  Control 

234.  Statistics  :  Abstainers'  Advantage 

235.  Chart  on  Smoker's  Heart  (I) 

236.  Chart  on  Smoker's  Heart  (II) 

237.  Chart  on  Smoker's  Heart  (III)    . 

238.  Deaths  from  Communicable  Diseases 

239.  Tuberculosis  Cure,  Summer 

240.  Tuberculosis  Cure,  Winter 

241.  Malarial  Swamp  .... 

242.  A  Model  Reservoir       .... 


LIST  OF  ILLUSTRATIONS 


XV 


FIGURE 

243.  A  Poor  Reservoir 

244.  Diagram  :  Thirty  Years  of  Diphtheria  in  New  York  State 

245.  Diagram  :  Story  of  Epidemic  of  Septic  Sore  Throat  at  Rockville 

Centre,  L.  I. 

246.  Model  Dairy  Cow 

247.  Model  Dairy  Stable      . 

248.  Map  Showing  Number  of  Dairy  Cows  on 

April  15,  1910 
Agar  Plates 
Bacteria  and  Mold 


249. 
250. 
251. 
252. 
253. 
254. 
255. 
256. 
257. 
258. 
259. 
260. 
261. 
262. 
263. 
264. 
265. 
266. 


Milk  Diluted  to  j^Vo 


Bean  Plant  .... 
Photograph  of  Bean  and  Pea 
Parts  of  Bean  Seed 
Diagram  of  Corn  Seed 
Sunflower  Seed    . 
Squash  Seed 
Germination  of  Bean   . 
Bean  Plants 
Sections  of  Bean  Root 
Root  Hairs  .... 
Root  Cap      .... 
Bean  Roots 

Fibrous  Roots  of  Buttercup 
Cross  Section  of  Bean  Leaf 
Leaf  Skeleton 

267.  Epidermis  of  Leaf 

268.  Germination  of  Corn    . 

269.  Rootlets  of  Two  Corn  Plants 

270.  Corn  Plant  .... 

271.  Maple  Seedlings  . 

272.  Microphotograph  of  Corn  Stem 

273.  Stem  of  Corn 

274.  Older  Maple  Seedlings 

275.  Seedlings      .... 

276.  Older  Horse-Chestnut  Seedlings 

277.  Wheat  Seedlings 

278.  Roots  of  Radish    . 

279.  Roots  of  Beet 

280.  Alfalfa  Root 

281.  Aerial  Roots  of  Ivy 

282.  Potato 


Farms  and  Ranges 


i'aci: 

241 
242 

243 
247 
248 

249 

250 

251 

252 

259 

260 

260 

262 

262 

262 

264 

267 

268 

269 

269 

270 

271 

273 

273 

274 

277 

277 

278 

279 

279 

280 

280 

281 

281 

28? 

282 

283 

283 

284 

285 


XVI 


LIST  OF  ILLUSTRATIONS 


308. 
309. 
310. 
311. 
312. 
313. 
314. 
315. 
316. 
317. 
318. 
319. 
320. 
321. 
322. 
323. 


FIGURE 

283.  Dahlia  Roots        ..... 

284.  Microphotograph  of  Sunflower  Stem  . 

285.  Cleft  Grafting       ..... 

286.  Whip  Grafting 

287.  Budding       ...... 

288.  Twining  Stem  of  Dodder     . 

289.  Creeping  Stem  of  Trailing  Arbutus 

290.  Horse-Chestnut    .... 

291.  Types  of  Twigs    ..... 

292.  Cherry  Twigs       . 

293.  Sections  of  Woody  Stem 

294.  Wood  of  Spruce 

295.  Photograph  of  Sections  of  Wood 

296.  Food  Storage 

297.  Celery  Plant 

298.  Cabbage  Plant 

299.  Twining  Petiole  of  Clematis 

300.  Twining  Petiole  of  Nasturtium    . 

301.  Barberry  Leaves  .... 

302.  Pea  Plant 

303.  Leaf  of  Oak 

304.  Leaf  of  Elm 

305.  Diagram  of  Bean  Flower     . 

306.  Diagram  of  Stamen  and  Pistil     . 

307.  Sweet  Pea  Flower       .... 
Fly  Pollinating  Wild  Carrot 
Swallow-Tail  Butterfly  Pollinating  Persian 
Corn  Flower  with  Pistils 
Pollen  Grains       ..... 
Pistillate  and  Staminate  Flowers  of  Willow 

Violet  

Two-Parted  Flower  of  Mint 

Lady  Slipper 

Flower  of  Columbine  .... 

Salvia 

Easter  Lily  ...... 

Fruit  of  the  Bean         .... 


Fruit  of  the  Corn 
Fruit  of  the  Poppy 
Capsule  of  Violet 
Chestnuts     . 


324.    Dry  Fruits 


Lilacs 


PAGE 

285 

286 

286 

287 

287 

288 

288 

288 

289 

289 

289 

290 

290 

291 

292 

292 

292 

292 

293 

294 

294 

294 

296 

297 

298 

298 

299 

299 

300 

301 

301 

303 

303 

304 

306 

306 

307 

307 

303 

308 

308 

309 


LIST  OF  ILLUSTRATIONS 


XV11 


FIGURE 

325. 

Vertical  Section  of  Apple    . 

326. 

Cross  Section  of  Apple 

327. 

Cross  Section  of  Orange 

328. 

Forms  of  Dehiscent  Fruits 

329. 

Fruits  with  Hooks 

330. 

Burdock  in  Blossom    . 

331. 

Fruits  Distributed  by  Wind 

332. 

Other  Fruits  Distributed  by  Wind 

333. 

Fruits  and  Seeds 

334. 

Milkweed  Plant    .... 

335. 

Seed  of  Cotton     .... 

336. 

Bean  Plant  Injured  by  Bacteria  . 

337. 

Beans  Damaged  by  Weevils 

338. 

A  Field  of  Beans 

339. 

Peanuts 

340. 

Map  of  Corn  Production 

341. 

Walnut  Tree 

342. 

Map  of  Production  of  Oats 

343. 

Map  of  Wheat  Production 

344. 

The  Cereals 

345. 

Lily-of-the-Valley 

346. 

X-Ray  of  Easter  Lily  . 

347. 

Leaves  and  Bud  of  Beech 

348. 

Wild  Columbine  . 

349. 

Stamens  and  Pistils  of  Rose 

350. 

Rose  Flower  Turning  into  a  Fruit 

351. 

Thorns  of  Rose    .... 

352. 

Map  of  Production  of  Orchard  Fruits 

353. 

Stipules  of  Rose  Leaf  . 

354. 

Flower  of  Mallow 

355. 

Water  Horehound 

356. 

Map  of  Cotton  Production  . 

357. 

Self-Heal     . 

358. 

Hedge  Nettle 

359. 

Common  White  Daisy 

360. 

Dandelion    . 

361. 

Map  of  Potato  Production 

362. 

Canada  Thistle     . 

363. 

Pleurococcus 

364. 

Spirogyra     . 

365. 

Spirogyra  Conjugating 

366.  Microphotograph  of  Conjugating  Spirogyra 


PAGE 

309 

309 

310 

310 

311 

311 

312 

312 

312 

313 

313 

315 

315 

317 

318 

319 

323 

324 

325 

326 

326 

327 

327 

328 

328 

329 

329 

330 

331 

331 

331 

332 

333 

333 

334 

334 

335 

336 

338 

340 

340 

341 


XV111 


LIST   OF   ILLUSTRATIONS 


FIGURE 

367.  Forms  of  Bacteria 

368.  Soil  Bacteria 

369.  Clean  Milk  . 

370.  Dirty  Milk   . 

371.  Beef  Jelly     . 

372.  Beef  Jelly    . 

373.  Bad  and  Good  Bottling 

374.  Yeast   .... 

375.  Fermentation  Tubes     . 

376.  Bread  Mold 

377.  Mold  Grown  from  Water 

378.  Cap  Fungi    . 

379.  Puffballs      . 

380.  Puffballs      . 

381.  Bracket  Fungus  . 

382.  Tree  Killed  by  Bracket  Fungus 

383.  Pear  Scab    . 

384.  Section  through  the  Scab 

385.  Spores 

386.  Lichens        . 

387.  Section  of  Lichen 

388.  Spores  of  Corn  Smut  . 

389.  Types  of  Mosses  . 

390.  Diagram  :   Life  History  of  Moss 

391.  Antheridial  Plant 

392.  Archegonial  Plant 

393.  Marchantia  . 

394.  Pteris  . 

395.  Pteris  Stem 

396.  Sori      . 

397.  Sori  Enlarged 

398.  Forked  Veins  of  Fern 

399.  Sporangia    . 

400.  Position  of  Sori  ;   Section  of  Sorus 

401.  Life  History  of  Fern    . 

402.  Sporangium  ;   Spores  . 

403.  Club  Moss   . 

404.  Horsetail 

405.  Selaginella  . 

406.  Conifers 

407.  Staminate  Strobili  of  Pine 

408.  Young  Cone  of  Pine  . 


PAGE 

343 

344 

348 

349 

350 

351 

352 

355 

355 

357 

357 

357 

358 

358 

359 

359 

359 

359 

360 

361 

361 

362 

364 

365 

365 

365 

367 

369 

370 

370 

370 

371 

371 

372 

372 

373 

373 

374 

374 

376 

377 

377 


LIST  OF  ILLUSTRATIONS 


XIX 


Pennsylvania 


FIGURE 

409.  Ripe  Cone  of  Pine 

410.  Other  Cones 

41 1.  Forest  of  Hard  Woods  and  Conifers  in  Northern 

412.  Lumbering  in  New  York      .... 

413.  Fire  Slash     ....... 

414.  Waste  Land  in  Pennsylvania 

415.  Waste  Land 

416.  Fire  Train  in  Adirondacks    .... 

417.  Nursery  where  Young  Trees  are  Started 

418.  Planting  Young  Trees  in  the  Adirondacks  . 

419.  Young  Plantation  in  the  Adirondacks  . 

420.  Young  Plantation  Sixteen  Years  after  Planting 

421.  Pollen  of  Pine      . 

422.  Seed  of  Pine 

423.  Photograph  of  Pitcher  Plant 

424.  Leaves  of  Pitcher  Plant 

425.  Photograph  of  Sundew 

426.  Diagram  of  Sundew     . 

427.  Venus's  Fly-Trap 

428.  Photograph  of  Birch  Roots. 

429.  White  Waterlily    . 

430.  Waterlilies  ;  Hydrophytes    . 

431.  Cat-Tails      .... 

432.  Giant  Cactus 

433.  Sage  Brush  .... 

434.  Diagram  :    Showing  Epidermis  o 

435.  Bull  Thistle 

436.  Lady  Slipper 

437.  Long-Spurred  Violet    . 

438.  Mistletoe      .... 

439.  Diagram  of  Sectional  View  of  a  Branch  Infected  with  Mistletoe 

440.  Tropical  Vegetation 

441.  CallaLily     .... 


Agave,  a  Zerophytic  Plant 


PAGE 

378 
378 
379 
380 
380 
381 
381 
382 
382 
384 
385 
386 
387 
387 
389 
390 
390 
391 
391 
392 
392 
393 
394 
395 
395 
396 
396 
397 
397 
398 
399 
401 
403 


PORTRAITS   OF    PROMINENT    BIOLOGISTS 


Darwin 
Agassi  z 
Huxley 
Koch     . 
Linnaeus 
Pasteur 


IM  IM.  v  \..r 

.  30 

.  100 

.  170 

.  235 

.  303 

.  348 


INTRODUCTION 

DEFINITIONS    OF   COMMON   BIOLOGICAL   TEEMS 

Biology  is  the  science  which  discusses  living  things — ■ 
plants,  the  lower  animals,  and  man.  These  living  things 
move,  breathe,  feel,  and  get  their  food  in  varied  ways. 

Man,  for  instance,  does  not  move  as  a  jellyfish  moves, 
nor  does  he  breathe  as  a  tree  breathes.  He  has  not  the 
same  sensations  as  a  frog,  nor  does  he  get  his  food  as  do 
the  flowers ;  though  lie  and  all  other  living  things  have 
these  functions1  in  common.  Each  living  thing  has  its 
parts  especially  adapted  to  its  peculiar  needs.  Claws 
serve  a  cat  admirably  for  climbinor  and  for  catching  mice; 
a  frog  has  web  feet  to  aid  in  swimming ;  while  hands  are 
better  suited  to  the  kind  of  things  that  a  man  has  to  do. 

Energy.  — Everything  that  plants  and  animals  do  re- 
quires energy.  Without  energy  in  some  form  they  can- 
not move  or  grow.  Energy  is  produced  in  various  ways. 
In  a  steam  engine  fuel  is  consumed  or  oxidized  to  make 
energy.  In  man  the  food  taken  into  the  body  is  con- 
verted into  energy  by  a  slow  kind  of  burning  which  we 
call  oxidation. 

Life  Processes.  —  From  the  study  of  physiology  we  are 
fairly  familiar  with  foods,  or  nutrients,  as  they  are  some- 
times called.  Some  of  these  are  starch,  sugar,  fats,  oils, 
and  mineral  matter.  The  life  of  a  plant  or  of  an  animal  is 
directly  dependent  upon  its  food.      But  food  is  not  the 


1  Function  has  a  scientific  use  in  biology,  where  it  is  used  to  describe  the 
common  living  activities  of  animals  and  l>'antMMMMH7    f  Bwn 

1     *  C  State  Oik* 


2  INTRODUCTION 

only  important  thing  to  consider  in  studying  its  life. 
The  life  of  each  plant  or  animal  may  be  studied  under 
eight  headings,  known  as  life  processes.  These  are  sensa- 
tion or  irritability,  locomotion,  food  getting,  digestion,  assimi- 
lation, respiration,  excretion,  and  reproduction. 

1.  Sensation  (irritability')  is  that  life  process  by  means 
of  which  an  organism  comes  to  know  of  things  outside  of 
itself.  Through  sensation  (irritability)  it  becomes  aware 
of  its  food.  By  the  help  of  the  senses  the  higher  animals 
are  able  to  see  and  hear  one  another,  are  conscious  of  heat, 
cold,  light,  sound,  and  many  other  things,  all  of  which 
are  called  stimuli. 

2.  Locomotion  is  the  life  process  by  which  animals  move, 
and  is  closely  related  to  sensation.  It  is  the  means  by 
which  animals  secure  food.  In  the  higher  animals  stimuli 
are  sent  through  the  nervous  system  to  the  various  muscles, 
which  contract  and  so  cause  the  animal  to  move. 

3.  Food  getting  needs  no  definition.  Man  gets  his  food 
from  many  sources.  He  eats  animals,  minerals,  and  vege- 
tables. Lower  animals  live  by  hunting  or  grazing,  and 
plants  get  their  food  through  their  leaves  and  roots. 

4.  Digestion  is  the  life  process  which  prepares  the  food 
to  pass  to  all  parts  of  the  body.  It  takes  place  in  all 
animals  and  plants,  but  we  are  most  familar  with  it  in 
man.  Man  chews  his  food  in  the  mouth,  thus  softening 
it  and  mixing  it  with  saliva  ready  for  the  stomach.  Di- 
gestion is  continued  in  the  stomach  and  completed  in  the 
intestine. 

As  soon  as  the  food  is  digested,  some  of  it  passes  through 
a  thin  membrane  in  the  wall  of  the  intestine  into  the 
blood  vessels  and  thus  is  ready  to  furnish  energy  in  the 
body.  This  passage  of  the  dissolved  food  through  a  mem- 
brane is  called  osmosis  (os-mo'sis). 

5.  Assimilation    is   the   building  of  the  digested  food 


LIFE   PROCESSES 


into  living  animal  and  plant  parts.  In  animals  the  blood 
vessels,  into  which  the  digested  food  passes,  carry  it  to  all 
parts  of  the  body,  and  as  it  circulates, 
each  part  takes  the  food  needed  and 
builds  it  into  living  material. 

6.  Respiration  is  the  life  process  that 
uses  oxygen  taken  from  the  air  or  water 
and  forms  a  waste  product  known  as 
carbon  dioxide.  This  life  process  should 
not  be  confused  with  breathing,  which 
is  limited  to  animals  with  lungs  or  air- 
tubes.  In  such  animals  the  breathing 
is  simply  a  mechanical  process  in  which 
the  air  is  brought  into  the  lungs  or 
air-tubes.  This  allows  the  oxygen  to 
pass  by  diffusion  into  the  blood,  where 
it  is  carried  to  all  parts  of  the  body,  or 
it  may  pass  directly  to  the  living  cells. 
See  section  6,  page  14. 

7.  Excretion  is  the  life  process  in 
which  waste  products,  like  perspiration, 
are  made  and  cast  off  by  the  body.  On 
page  1  we  saw  that  energy  was  pro- 
duced by  oxidation.  After  this  the 
waste  is  thrown  off  by  excretion,  as 
the  ashes  are  thrown  out  of  a  steam 
engine. 

8.  Reproduction  is  the  life  process  by  means  of  which 
each  generation  of  plants  and  animals  is  brought  forth. 
There  are  two  kinds,  asexual  (a'sex-u-al)  and  sexual. 
Figure  47  on  page  49  shows  a  simple  animal,  the  amoeba 
(a-me'ba),  dividing  into  two  young  amoebae  by  asexual 
methods.  The  same  kind  of  reproduction  in  a  simple 
plant,  the  yeast,  is  illustrated  in  Figure  374,  page  355. 


Figure  1 .  —  Simple 
Osmometer  show- 
ing Osmosis. 

The  water  in  the 
glass  passes  through 
the  egg-membrane 
and  forces  the  egg- 
white  up  in  the  glass 
tube  ;  while  the  egg- 
white  does  not  pass 
out  into  the  sur- 
rounding water. 


INTRODUCTION 


Figure  2.  —  Plant  Cell. 


Sexual  reproduction  is  the  name  given  to  a  process  in 
which  two  special   cells,  called   the  egg  and   the  sperm, 

unite  to  form  one  cell,  the 
fertilized  egg  cell.  The  fer- 
tilized egg  grows  into  the 
new  organism.  In  some 
plants  the  fertilized  egg 
forms  part  of  a  seed  which 
later  develops  into  the  plant. 
These  eight  life  processes 
are  seen  in  all  forms  of  liv- 
ing things,  but  it  is  often 
hard  to  stuclv  them.  For 
instance,  the  locomotion  of  a  clam  is  harder  to  study 
than  that  of  a  cat,  and  the  respiration  of  a  plant  than  that 
of  a  man. 

The  Parts  of  Bodies.  —  These  life 
processes  tell  us  what  the  parts 
of  bodies  do,  but  they  tell  us 
nothing  about  these  parts  them- 
selves. There  are  four  words 
which  are  used  in  biology  to 
describe  these  parts.  They  are: 
cell,  tissue,  organ,  and  organ 
system. 

1.  The  Cell.  —When  the  bi- 
ologist takes  apart  the  plant  or 
animal  as  you  used  to  take  down 
your  block  houses,  he  finds  that 
he  can  separate  the  parts  until 
he  comes  to  a  unit  so  small  that 
a  microscope  is  necessary  to  see 

it.      These    microscopic    parts    are    called    cells   and    are 
alike   in   the    following   respects  :     each   one   has  a  clear 


Figure  3.  —  Animal  Cell. 


THE   PARTS   OF   BODIES 


outer  portion  called  the  cell  wall  which  incloses  a  mass  of 
substance  known  as  protoplasm  (pro'td-plaz'm  :  Greek, 
protos,  first;  plasma,  form).  The  protoplasm  is  made  up 
of  a  substance  called  cytoplasm  (sl'tu-plaz'm  :  Greek,  kytos, 
hollow  place  ;  plasma,  form),  in  which  is  held  a  saclike 
body,  the  nucleus  (nu/kle-us  :  Latin,  nucleo,  to  become 
hard).  The  nucleus  usually  contains  one  or  more  separate 
bodies  called  nucleoli  (nfi/kle-6-li).  A  cell  is  therefore 
defined  as  a  mass  of  protoplasm  composed  of  cytoplasm  and 
nucleus  (Figures  2  and  3). 

2.  Tissue.  —  The  cells  are  of  many  shapes  and  sizes, 
and  in  the  bodies  of  all  but  microscopic  plants  and  animals 
are  united  to  help  the 
plant  or  animal  carry 
on  its  life  processes. 
This  union  of  cells  to 
do  a  certain  work  is 
called  a  tissue,  and  the 
usual  definition  is  :  a 
tissue  is  a  group  of  simi- 
lar cells  that  do  a  similar 
work  (Figure  4). 

3.  Organs. — In  all  of 
the  higher  animals  the 
tissues  are  united  into 
skin,  arms,  stomach, 
and  so  on,  or  in  plants  into  leaf,  branch,  etc.  Such  struc- 
tures are  called  organs ;  an  organ  is  defined  as  a  group  of 
tissues  that  do  a  given  work  in  the  animal  or  plant. 

4.  The  Organ  System.  —  When  different  organs  com- 
bine to  carry  on  such  a  general  life  process  as  digestion, 
all  of  the  parts  that  assist  in  this  process  are  described  as 
an  organ  system,  as  the  system  of  digestive  organs  (Fig- 
ures 178  and  179,  pages  163  and  165). 


Figure  4.  —  Tissue. 
Compare  these  cells  with  Figures  2  and  3. 


6  INTRODUCTION 

These  four  expressions,  cell,  tissue,  organ,  and  organ  sys- 
tem, describe  the  materials  of  plants  and  animals  which 
carry  on  the  eight  life  processes  referred  to  above.  We 
shall  read  more  and  more  about  them  as  our  study  of 
biology  progresses. 

Classification  of  Living  Things.  —  Our  study  of  biology 
cannot  progress  far  before  we  see  the  need  of  classifying 
animals  and  plants.  Animals  are  generally  grouped  in 
two  divisions :  invertebrates  (animals  without  backbone) 
and  vertebrates  (animals  with  backbone).  Plants  are  also 
divided  into  two  groups :  cryptogams  (flowerless  and  seed- 
less plants)  and  phanerogams  (flowering  or  seed-bearing 
plants).  Below  is  given  a  detailed  reference  table  of 
these  classifications. 

I.    Invertebrates.     Animals  without  a  backbone. 

1.  Protozoa.     8000  different  kinds. 

a.  Rhizopoda.     Example,  the  amoeba. 

b.  Ciliata.     Example,  the  paramoecium. 

2.  Porifera.     Sponges,    2500   different   kinds.      Example,  the   bath 

sponge  and  grantia. 

3.  Ccelenterata.     Hydra,  corals,  and  jellyfish.     4500  different  kinds. 

a.  Hydrozoa.     Example,  the  hydra,  obelia,  pennaria. 

b.  Scyphozoa.     The  large  jellyfishes. 

c.  Actinozoa.     The  corals. 

4.  Echinoderms.     Starfishes  and  sea  urchins.     4000  different  kinds. 

5.  Worms    and    wormlike   animals.      Examples,    flat   worms,    tape 

worms,  earthworms.     11,000  different  kinds. 

6.  Mollusca.     The  clams  and  snails.     61,000  different  kinds. 

a.  Pelecypoda.     Example,  clams. 

b.  Gastropoda.     Example,  snails. 

c.  Cephalopoda.     Example,  squids,  devilfish. 

7.  Arthropoda.      Crabs  and  insects.      400,000  different  kinds. 

a.  Crustacea.     Example,   crayfish  and  crabs.      10,000  different 

kinds. 

b.  Insecta.     Example,     grasshopper,     flies,     butterflies,     bees. 

390,000  different  kinds. 
II.    Vertebrates.     Animals  with  a  backbone. 

1.   Fishes.     Examples,  trout,  perch,  bass,  cod.    13,000  different  kinds. 


SCIENTIFIC   TERMS  7 

2.  Amphibia.     Example,  frog,  salamander.     14,000  different  kinds. 

3.  Reptilia.     Example,  snakes,   turtles,   alligators.     35,000  different 

kinds. 

4.  Birds.     Example,  sparrow,  eagle,  hawk,  crow.     13,000  different 

kinds. 

5.  Mammals.     Example,  horse,   cow,  sheep,  monkey,  man.     35,000 

different  kinds. 

The  plants,  like  the  animals,  are  arranged  in  general 
groups  (phyla)  which,  beginning  with  the  simplest,  are  as 
follows  : 

I.    Cryptogams.     Flowerless  or  seedless  plants. 

1.  Thallophytes. 

a.  Bacteria.     1300  different  kinds. 

b.  Algse.     Example,    pleuroccocus,    spirogyra.      1300     different 

kinds. 

c.  Fungi.     Example,  molds,  puff-balls,  toadstools.     64,400  dif- 

ferent kinds. 

2.  Bryophytes. 

a.  Liverworts.     4000  different  kinds. 

b.  Mosses.     12,600  different  kinds. 

3.  Pteridophytes.     4500  different  kinds  of  ferns. 
II.    Phanerogams.     Flowering  or  seed-bearing  plants. 

1.  Gymnosperms.     Example,  pine,  spruce.     540  different  kinds. 

2.  Angiosperms.     Flowering  plants  proper. 

a.  Monocotyledons.     Example,  corn.     23,700  different  kinds. 

b.  Dicotyledons.     Example,  bean.     108,800  different  kinds. 

Scientific  Terms.  —  Scientists  in  America,  France,  Ger- 
many, Russia,  and  elsewhere  are  continually  studying 
different  plants  and  animals.  For  their  convenience  the 
Latin  names  are  usually  adopted  in  advanced  scientific 
works.  Thus  the  English  or  house  sparroiv  is  called  .Pasxrr 
domesticus,  and  the  American  elm,  Ulmus  americana,  so  that 
scientists  of  different  countries  may  always  use  the  same 
term.  But  in  this  book  we  shall  use  the  common  Ameri- 
can names  of  the  plants  and  animals  studied. 

Scientific  terms  include  also  the  names  of  certain  suit- 
stances  frequently  referred  to  in  science  books  like  this 


8 


INTRODUCTION 


Nitrogen 


Sulphur 
Phosphorus 
Calcium 
etc 


Biology.     Before  going  farther  it  is  well  to  get  a  clear  idea 
of  what  the  common  chemical  terms  mean. 

1.  Oxygen  is  a  gas  which  makes  up  a  large  part  of  the  air. 
It  is  the  element  in  the  air  which  sustains  life  in  animals 
and  plants.     Without  it  they  cannot  live.     When  given 

an  undue  amount  of  it, 
they  develop  at  an  ab- 
normal rate.  It  forms 
about  seventy  per  cent 
of  the  bodies  of  plants 
and  animals. 

The  most  striking 
property  of  oxygen  is 
the  ease  with  which  it 
unites  with  other  sub- 
stances. Practically  all 
cases  of  burning  are 
caused  by  oxygen  unit- 
ing with  paper,  wood, 
coal,  or  some  other  material.  If  a  piece  of  glowing 
charcoal  is  placed  in  a  jar  of  oxygen,  it  bursts  into  flame. 
This  is  the  test  for  oxygen. 

2.  Carbon  is,  next  to  oxygen,  one  of  the  most  important 
elements  in  biolog}^.  It  is  usually  black  and  solid  and  is 
best  seen  as  the  charred  remains  of  any  material  that  has 
been  overheated  but  not  burned  up,  as  when  toast  or  meat 
is  "  burned."  Carbon  forms  about  fourteen  per  cent  of  the 
body  of  plants  and  animals. 

3.  Hydrogen  gas  is  the  lightest  of  all  substances.  For 
this  reason  it  is  used  in  balloons  and  Zeppelins.  It  forms 
a  little  less  than  ten  per  cent  of  the  body  of  plants  and 
animals. 

4.  Nitrogen  is  a  gas  which  —  unlike  oxygen  and  hydro- 
gen —  does  not  burn.     It  dilutes  the  oxygen  of  the  air  and 


Figure  5.  —  Diagram. 

Showing  proportion  of  chemical  ele- 
ments in  living  things. 


ORGANIC  AND  INORGANIC   MATTER  9 

so  makes  it  less  active.  Nitrogen  forms  less  than  three 
per  cent  of  the  body  of  plants  and  animals. 

5.  Calcium.,  sulphur,  phosphorus,  iron,  and  potassium  are 
the  other  important  elements  found  in  living  things.  None 
of  these  elements  forms  as  much  as  one  per  cent  of  the  body 
of  plants  or  animals. 

Chemical  Compounds.  — All  these  chemical  elements  com- 
bine with  each  other  to  form  definite  substances  called 
chemical  compounds,  which  we  can  see  and  handle.  Oxy- 
gen and  nitrogen  mixed  together  make  up  about  ninety- 
nine  per  cent  of  the  atmosphere ;  hydrogen  and  oxygen 
unite  to  form  water ;  carbon,  hydrogen,  and  oxygen  unite 
to  form  starch  and  sugar. 

The  union  of  oxygen  with  any  other  substance  produces 
heat  or  energy.  This  uniting  is  called  oxidation.  When 
oxygen  unites  with  carbon  in  our  bodies,  carbonic  acid  gas 
(carbon  dioxide)  is  formed  and  heat  is  produced.  The 
production  of  heat  is  one  of  the  most  important  of  the 
changes  that  take  place  in  living  things. 

Physical  and  Chemical  Change.  —  If  a  solid  piece  of  ice  is 
melted,  it  becomes  liquid  water.  If  the  liquid  water  is 
boiled,  it  becomes  steam,  vapor,  or  gas.  If  the  steam  is 
condensed,  it  becomes  water,  which  in  turn  may  again  be 
frozen  into  ice.  Any  change  in  a  substance  which  does 
not  alter  the  material  of  which  it  is  composed  is  called  a 
physical  change. 

On  the  other  hand,  when  oxygen  unites  with  wood,  the 
wood  burns,  giving  off  heat  and  smoke,  and  asli  remains. 
But  this  ash  cannot  be  united  with  heat  and  smoke  to  form 
the  original  wood.  Such  a  change  as  is  seen  in  the  burn- 
ing of  wood  is  called  a  chemical  change. 

Organic  and  Inorganic  Matter.  — It  is  customary  to  separate 
chemical  compounds  which  are  made  in  living  things  from 
those  which  are  made  outside  the  bodies  of  plants    and 


10  INTRODUCTION 

animals.  All  matter  such  as  wood,  sugar,  and  meat, 
which  is  made  in  living  things,  is  called  organic  matter. 
All  matter  like  stones  and  water,  which  is  made  outside 
of  living  things,  is  called  inorganic. 

Environment.  —  Plants  and  animals  have  accustomed 
themselves  to  live  in  different  parts  of  the  world.  .  Their 
behavior  and  habits  under  these  varying  conditions  form 
a  most  interesting  part  of  the  study  of  biology.  The  sur- 
roundings of  plants  and  animals,  that  is,  the  different  con- 
ditions, the  air,  water,  climate,  and  soil  in  which  they  live, 
are  called  their  environment. 


PRACTICAL  BIOLOGY 


PART   I 


ANIMAL   BIOLOGY 


CHAPTER   I 


THE  GRASSHOPPER,   A   REPRESENTATIVE   ANIMAL 

1.  Live  Animals. — We  all  know  that  animals  are  alive, 
just  as  men  and  plants  are  alive,  and  we  naturally  want 
to  know  how  they  live,  what  parts  of  their  bodies  they 
use  in  eating  and  breathing,  and  how  they  escape  their 
enemies.  After  we  have  learned  about  the  lower  animals, 
we  can  compare  them  with 
plants  and  with  man,  and  it 
will  be  interesting  to  learn 
in  what  ways  all  living 
things  are  alike. 

When  the  study  of 
Biology  begins  with  ani- 
mals,  all  that   is  necessary 

is  to  select  an  animal  that  can  be  conveniently  found 
and  watched ;  and  then  to  try  to  learn  where  it  lives, 
what  it  does,  how  it  produces  its  young,  and  what 
relation  it  has  to  mankind.  Material  for  study  is  easily 
obtained  wherever  you  happen  to  live,  whether  in  the 
city,  the  country  town,  or  on  the  prairies.  A  nearby 
park  or  vacant  lot,  the  fields,  the   woods,  or  the   plains, 

u 


Figure  6. — Female    Grasshopper. 


12 


THE   GRASSHOPPER 


whichever  you  can  reach  most  easily,  will  supply  you 
with  a  collection  of  insects,  if  you  look  carefully. 

All  insects  will  be  found  doing  something.  Some  will 
be  flying  from  flower  to  flower,  and  you  can  watch  to  see 
what  they  are  doing;  others  will  be  busy  on  the  leaves  or 
the  stems,  and  a  few  minutes  of  observation  will  show  you 
whether  they  are  friends  or  foes  of  the  plant  upon  which 
you  find  them.  The  most  interesting  way  to  study  in- 
sects is  to  watch  them  in  their  home  life,  but  when  this 
cannot  be  done,  they  can  be  well  studied  in  the  laboratory. 
Even  in  a  large  city  a  surprisingly  large  number  of  kinds 
of  insects  can  be  collected  by  a  class  and  brought  alive 
to  the  laboratory. 

2.  The  Grasshopper.  —  The  study  of  animals  begins  in 
this  book  with  the  grasshopper.  When  during  the  late 
summer  we  walk  into  the  fields  or  along  paths  lined  with 
grass,  we  are  often  surprised  at  the  number  of  grasshop- 
pers which  jump  away  as  we  approach.  They  are  of  va- 
rious sizes  and  kinds.  Some  are  small  and  without  wings, 
while  others  have  small  but  well-formed  wings.  The 
difference  in  the  wings  and  in  the  shape  of  the  body  tells 
us  that  there  are  various  kinds  of  grasshoppers. 

FIELD   STUDY 

To  study  living  insects.  Collect  insects  such  as  grasshoppers,  crickets, 
beetles,  bees,  wasps,  flies,  moths,  butterflies,  etc.  Place  some  under 
tumblers  and  complete  your  report  as  follows  : 


o 

32 

05 

0 
W 

Mouth  Parts 

Where  Found 

H 
a   x 

-  5 

6 

—  f. 

-  C 
~.   Z. 

Size  oi 
Wings 

Size  oi 
Third 

p 

T3 
CD 

CD 

3 

House  fly  . 

On  food  in  the  home 

2 

Small 

Grasshopper 

On  grass  in  the  field 

6 

4 

Medium 

Moth    .     . 

On  flowers  in  the  park 

6 

4 

Large 

LIFE  PROCESSES 


13 


3.  Life  Processes  of  the  Grasshopper.  —  The  young  grass- 
hopper must  escape  being  eaten,  must  find  food,  must  have 
oxygen  to  breathe,  must  develop  into  an  adult,  and  must 
do  its  part  in  providing  for  another  generation  of  grass- 
hoppers. If  the  grasshopper  fails  in  any  one  of  the  first 
three  of  these  necessities,  it  is  unable  to  live,  and  conse- 
quently the  last  and  most  important  work,  that  of  provid- 
ing for  the  next  generation,  is  not  possible. 


LABORATORY   STUDY 

Examine  a  live  grasshopper.  What  are  its  means  of  locomotion  ? 
Compare  its  jump  with  its  length.  If  in  the  same  proportion,  how  far  could 
a  man  six  feet  tall  jump  ?  How  does  the  grasshopper  obtain  food  ?  What 
protection  from  enemies  does  it  gain  from  its  color  ?  Notice  the  divi- 
sion of  the  body  into  three  regions ;  head,  thorax  (tho'raks)  which  has 
wings,  and  abdomen  (ab-do'men).  When  the  living  grasshopper  is  held 
between  the  thumb  and  finger,  it  "  spits  molasses."  This  is  the  partially 
digested  food  from  its  crop. 

4.  Protection  —  When  we  look  closely  at  the  grass- 
hopper, we  find  that  it  is  provided  with  many  character- 


N>7U.'oU!. 


J/bdomen 


PntT.-rax 


Figure  7.  —  Diagram. 
Showing  the  main  parts  of  the  grasshopper. 

istics  which  prevent  its  being  caught  and  eaten.  The 
most  important  of  these  are  its  color  and  markings. 
When  a  grasshopper  jumps    into  the  grass  and  remains 


14 


THE  GRASSHOPPER 


ibru 


abrum 


ndibU 


mandible 


ndiblf 


mandible 


'.;)  nupo  pharynx 


quiet,  its  color  so  closely  resembles  the  grass  and  the 
sticks  that  many  of  its  enemies  overlook  it.  This  is  an 
example  of  what  is  called  protective  coloration.  The  grass- 
hopper is  further  protected  by  a  pair  of  large  eyes  and  by 
simple  ears  which  are  located  on  the  side  of  the  body.  By 
means  of  these  sense  organs,  it  becomes  aware  of  the 
presence  of  enemies.  The  quickness  of  grasshoppers  in 
jumping  also  helps  them  to  escape  being  eaten. 

5.  Food  Getting.  —  The  grasshopper  has  little  difficulty 
in  finding  its  food.     It  eats  leaves,  and  particularly  the 

leaves  of  grass.  It  does 
not  need  a  keen  sense  of 
smell,  as  does  the  bee 
which  must  search  for 
flowers.  However,  the 
grasshopper  has  special 
smelling  organs  located 
in  its  antennas  (£n- 
ten'e),  those  long  feelers 
which  grow  out  from 
the  head  like  soft  horns. 
The  mouth  parts 
which  cut  and  chew  the 
food  consist  of  an  upper 
lip  and  two  teeth  (mandibles,  man'di-b'ls).  The  teeth 
are  moved  by  powerful  muscles  which  nearly  fill  the 
head.  These  mandibles  work  from  side  to  side,  instead 
of  up  and  down  as  our  teeth  do.  They  are  so  effective 
that  sometimes  when  grasshoppers  become  numerous 
they  strip  the  grass  of  all  its  leaves,  and  even  destroy 
growing  fields  of  grain. 

6.  Breathing.  —  All  animals  have  some  way  of  getting 
oxygen  to  every  portion  of  their  bodies  and  of  getting  rid 
of  carbon  dioxide.     The  grasshopper  has  no  lungs  such  as 


(  in 


maxilla 


maxi  ila 


biu 


a  bium 


Figure  8.  —  Mouth  Parts  of  the 
Grasshopper. 


LIFE  HISTORY 


15 


ours,  nor  does  it  breathe  through  its  mouth.  On  each 
side  of  the  body  are  found  a  number  of  regularly  arranged, 
small  openings,  spiracles  (spir'a-k'ls),  which  lead  into  * 
branching  tubes,  traehece  (tra/ke-e).  These  tubes  carry 
air  to  all  parts  of  the  body  in  order  that  the  cells  may  be 
able  to  take  the  oxygen  from  the  air  and  give  carbon 
dioxide  to  it.  The  cell  process  in  which  oxygen  is  used 
and  carbon  dioxide  formed  is  called  respiration.  See 
section  6,  page  3. 

7.  Reproduction  and  Life  History.  —  In  the  autumn,  the 
female  grasshopper  lays  her  eggs  in  a  hole  which  she 
makes  in  the  ground. 
The  eggs  remain  in  the 
hole  until  the  following 
spring,  when  they  hatch 
into  wingless  grasshop- 
pers. Their  bodies  are 
covered  by  a  firm  skin, 
called  the  exoskeleton, 
which  does  not  increase 
in  size  as  the  grasshop- 
pers grow,  so  this  skin 
must  be  shed  to  allow 
room  for  growth. 

Young  grasshoppers,  like  young  children,  grow  rapidly; 
therefore  the  grasshoppers  have  to  shed  their  skeleton  often 
and  grow  a  new  and  larger  one.  The  scientific  term  for  this 
shedding  of  the  old  skeleton  and  the  growing  of  a  new  is 
molt  (molt).  In  the  early  spring  and  summer,  the  young 
grasshopper  molts  again  and  again,  each  time  growing 
a  little  more  like  the  adult  grasshopper.  This  process 
of  growth  takes  three  or  four  months.  After  the  last 
molt,  it  has  wings  and  can  fly,  and  so  is  a  full-grown 
grasshopper. 


Figure  9. 

a,  Grasshopper  laying  Eggs  ;  b.  Egg- 
capsule  ;    c,  Eggs. 


16  THE  GRASSHOPPER 

LABORATORY  STUDY 

Work  out  the  divisions  of  the  body  of  the  grasshopper  :  head,  thorax, 
and  abdomen;  the  position  of  eyes.  How  are  the  antennae  related  to 
the  eyes  ?  How  many  distinct  mouth  parts  are  there  ?  The  teeth  or 
jaws  are  the  most  useful  in  getting  food.  How  do  the  jaws  work  ? 
Sketch  the  head  to  show  these  parts  with  the  mouth  open. 

Notice  the  attachment  of  the  head  to  the  thorax.  The  head  fits  into 
the  thorax.  The  loose  anterior  (front)  portion  of  the  thorax  is  the  pro- 
thorax  (forward  thorax).  The  first  pair  of  legs  is  attached  to  it.  Sketch 
the  prothorax  to  show  it  and  its  legs.  The  portion  of  the  thorax  back  of 
the  prothorax  is  divided  into  two  regions:  the  mesothorax  (middle 
thorax)  and  the  metathorax  (back  thorax).  The  line  between  them  is 
not  clear.  Sketch  these  parts  together  with  the  legs  and  the  wings.  The 
jumping  legs  are  attached  to  the  metathorax  ;  the  outer  wings  to  the 
mesothorax ;  the  inner  wings  to  the  metathorax.  The  inner  wings  are 
used  in  flying.  The  leg  of  the  grasshopper  consists  of  :  (1)  a  small 
section  close  to  the  body  (the  coxa)  ;  a  long  muscular  part  free  from 
spines  (femur) ;  a  slender  spiny  part  (tibia) ;  and  the  three  segments  of 
the  foot  (tarsus) .  The  last  segment  of  the  foot  is  furnished  with  hooks 
which  help  the  grasshopper  in  climbing,  while  the  spines  on  the  tibia  pre- 
vent slipping  as  the  grasshopper  jumps.  The  large  muscles  in  the  femur 
of  the  last  pair  of  legs,  the  spines  on  the  tibia,  and  the  hooks  on  the  tarsus, 
are  special  adaptations  which  help  the  grasshopper  in  various  ways. 

Notice  the  tapering  abdomen,  composed  of  ten  segments  (rings)  or 
parts  of  segments.  Notice  the  depression  and  membrane  in  the  first 
segment.  This  is  the  auditory  organ,  but  it  is  not  a  true  ear.  Sketch 
the  abdomen  to  show  its  features.  The  spiracles  are  located  on  the  sides 
of  the  abdomen. 

8.  Metamorphosis.  —  All  animals  which  pass  through  a 
marked  change  in  external  appearance  as  they  become  full 
grown  are  said  to  undergo  a  metamorphosis  (met-a-m6V- 
fo-sis  :  Greek,  meta,  change;  morphe,  form).  These 
changes  are  more  marked  in  such  insects  as  the  ants  and 
bees  than  in  the  grasshopper.  For  this  reason  we  speak 
of  two  forms  of  metamorphosis  —  complete  and  incomplete. 

9.  Incomplete  Metamorphosis.  — The  newly  hatched  grass- 
hopper, while  very  small,  looks  enough  like  a  wingless 
grasshopper  to  be    identified  as  belonging  to   the  grass- 


COMPLETE   METAMORPHOSIS 


17 


hopper  family.  Its  form 
does  not  change  materi- 
ally from  the  time  it  is 
hatched  until  it  is  full 
sized.  Thus  the  grass- 
hoppers become  adult 
by  a  growing  process 
termed  incomplete  meta- 
morphosis, showing  no 
marked  change  in  form 
(Figure  10). 

10.  Complete  Metamor- 
phosis. —  Certain  other 
insects,  for  example  the 
codling  moth,  hatch  into 
caterpillars  from  the 
eggs  that  the  female  lays 
in  the  apple.  These 
caterpillars  are  known 
as  larvae  (dar've  :  Latin, 
larva,  mask).  The  larvae 
of  the  codling  moth  are 

the  "  worms  in  the  apple."     These  larvae  are  not  recog- 
nized from  their  external  appearance   as  young  codling 


—     - 


Figure  10. —  Incomplete  Metamor- 
phosis of  the  Tree  Cricket. 

The  tree  cricket  belongs  to  the  same 
family  of  insects  as  the  grasshopper. 


Figure  11.  —  Codling  Moth  Larva. 


18 


THE   GRASSHOPPER 


moths,  yet  that  is  what  they  are.     As  the   larva  eats  a 
great   deal,   it   grows   rapidly,  molting   again   and  again 

until  it  becomes  a 
full-sfrown  cater- 
pillar.  It  then  eats 
its  way  out  of  the 
apple  where  it  has 
been  living  its  lar- 
val life  for  several 
weeks. 

In  some  pro- 
tected spot,  under 
the  bark  scales, 
the     full-grown 

„,  „        caterpillar     then 

Figure  12. —  "The  Worm  in  the  Apple.'  l 

weaves  a  silken 
covering  (the  cocoon,  ko-koon/)  about  itself.  In  this 
cocoon  it  molts  again.     When  this  last  molt  occurs,  the 


Figure  13.  —  Codling  Moth  Pupa. 


caterpillar   loses   its   legs  and   mouth  parts,  and  is  now 
known  as  a  pupa  (pu'pa).     The  pupa  does  not  eat,  but 


STRUCTURE 


19 


continues  to  breathe.  Thus  we  speak  of  this  stage  in 
the  growth  of  the  codling  moth  as  the  "resting  stage" 
This  resting  stage  of  the  codling  moth  pupa  l  is  very 
short.  Then  a  linal 
molt  takes  place  and  the 
fully  formed  codling 
moth  crawls  from  the 
cocoon  (Figures  11-14). 

This  series  of  changes 
through  which  the  cod- 
ling moth  passes  from 
egg      into      caterpillar,  FlGURE  14._CoDLING  MoTH. 

then     into     pupa,     and 

finally  into  full-grown  moth,  is  termed  complete  meta- 
morphosis. Ants,  bees,  butterflies,  beetles,  and  certain 
other  insects,  all  undergo  complete  metamorphosis. 

There  are  a  number  of  different  terms  used  to  describe 
the  larval  stage  of  insects : 

caterpillars  are  the  larvae  of  butterflies  and  moths. 

grubs  are  the  larvae  of  beetles. 

"  wigglers  ' '  are  the  larvae  of  mosquitoes. 

maggots  are  the  larvae  of  flies. 

currant  worms  are  caterpillars. 

measuring  worms  are  caterpillars. 

11.  Structure  and  Classification  of  the  Grasshopper. —  In 
order  to  understand  the  grasshopper  more  fully  it  is 
necessary  to  find  its  place  in  the  classification  of  animals. 
All  animals  that  are  known  have  been  grouped  into  classes 
for  convenience  in  study.  The  grasshopper  belongs 
to  the  large  class  of  animals  called  Insecta  (In-sek'ta  : 
Latin,  in,  in;   seco,  cut). 

The  insects,  as  a  class,  have  their  bodies  divided   into 


Larvae 


1  Sometimes   the  codling   moth   passes   into   the   pupa   stage   in   the  fall, 
thus  living  through  the  winter  in  the  "  resting  stage." 


20 


THE  GRASSHOPPER 


three  regions — head,  thorax,  and  abdomen.  See  Figure  7. 
All  have  three  pairs  of  legs,  and  most  of  them  two  pairs 
of  wings.  .  They  breathe  by  means  of  air  tubes  (tracheae'). 
In  becoming  adult,  all  pass  through  metamorphosis,  either 

complete  or  incomplete.  The 
insect  group  is  subdivided 
into  ten  smaller  groups  or 
orders. 

The  grasshopper  belongs  to 
the  order  known  as  Orthop- 
tera1  (6r-thop'ter-a  :  Greek, 
orthos,  straight; pteron,  wing). 
In  the  Orthoptera  we  find  six 
common  families  :  grasshop- 
jDers,  crickets,  katydids,  cock- 
roaches, walking  sticks,  and 
praying  mantids. 

12.   Economic    Insects.  —  By 
economic    insects,    we    mean 
those  insects  which,  by  their 
activities,  are  either  helpful 
or  harmful  to  man.     If  an  insect  has  no  economic  impor- 
tance, we  mean  that  it  does  not  harm  us  by  eating  things 
useful  to  us,  nor  does  it  help  us  in  any  way. 

The  struggle  to  live  is  a  problem  for  all  animals,  for 


Figure  15.  —  Monarch  Butterfly. 

Showing  how  it  carries  pollen 
from  one  clover  blossom  to 
another. 


1  grasshoppers,  katydids,  crickets 
butterflies  and  motbs 
beetles 
bugs 

bees,  wasps,  ichneumons,  gall  flies 
flies  and  mosquitoes 
dragon  flies 
May  flies 
stone  flies 
fleas 


(straight  wings) 
(scaly  wings) 
(shield  wings) 
(half  wings) 
(membrane  wings) 
(two  wings) 
(teeth) 
(short  lived) 
(net  wings) 
(wingless) 


often  called  siphon-mouthed 


Orthoptera 

Lepidoptera 

Coleoptera 

Hemiptera 

Hymenoptera 

Diptera 

Odonata 

Ephemeridae 

Plecoptera 

Aptera 

Siphonaptera 


ECONOMIC  INSECTS 


21 


man  as  well  as  for  the  grasshopper.  All  insects  must  eat, 
and  some  eat  the  same  things  we  wish  to  eat.  Such  in- 
sects we  call  harmful.  Others  aid  the  growth  of  plants 
by  carrying  the  pollen  dust  from  one  flower  to  another  ; 


Figure   16.  —  Modern  Spraying  Outfit. 
Used  to  destroy  harmful  insects. 

others  make  honey.  Such  insects  are  useful.  Certain 
other  insects,  like  the  fly,  carry  the  germs  of  disease. 
These  insects  are  particularly  harmful,  for  they  cause 
sickness  and  death. 


22  THE  GRASSHOPPER 

Certain  beetles  eat  dead  flesh  or  bury  dead  animals 
by  tunneling  under  them.  Such  insects  are  helpful. 
We  should  study  insects  in  order  to  find  out  which 
are  our  friends  and  which  our  enemies.  It  would  not  do 
to  kill  all  kinds  of  insects,  for  in  many  cases  we  should 
harm  ourselves. 

13.  Economic  Phases  of  the  Grasshopper.  —  The  grasshopper 
eats  the  leaves  of  plants,  and  if  there  are  many  grass- 
hoppers, they  cause  a  serious  loss  of  crops.  The  plague  of 
locusts  mentioned  in  the  Bible  refers  to  grasshoppers.  In 
some  of  the  Western  States  years  ago  the  grasshoppers 
came  in  great  swarms  year  after  year  and  destroyed 
annually  crops  estimated  to  be  worth  1200,000,000. 
But  ordinarily,  owing  to  the  activities  of  their  natural 
enemies,  the  number  of  grasshoppers  does  not  become 
alarming. 

Among  the  natural  enemies  of  these  insects  that  do  much 
toward  reducing  their  number  are  the  birds.  Some  of 
the  greatest  destroyers  of  grasshoppers  are  the  quail,  blue- 
bird, sparrow  hawk,  butcher  bird,  crow,  red-winged 
blackbird,  and  kingbird.  The  crows,  because  of  their 
large  size  and  great  numbers,  probably  kill  the  most 
grasshoppers. 

Other  members  of  the  order  of  Orthoptera,  that  are 
more  or  less  harmful,  are  the  cockroaches,  the  nuisances 
of  the  pantry,  and  the  crickets  that  eat  the  roots  of  plants. 
There  are  also  tree  crickets  which  frequently  lay  their 
eggs  in  raspberry  cane  and  kill  the  cane  above  the  place 
where  the  egg  is  laid. 

14.  What  has  an  Animal  like  the  Grasshopper  Accomplished 
by  Living? — (1)  It  has  used  plants  as  food  to  build  a 
complex  body.  (2)  It  has  produced  more  grasshoppers. 
(3)  It  has  used  some  stored-up  food  which  might  have 
been  useful  to  cattle  or  sheep.     (4)   It  has  set  free  waste 


QUESTIONS  23 

carbon  dioxide  which  can  be  used  by  green  plants  to  assist 
them  in  making  food.  (5)  When  it  dies  and  decomposes, 
its  chemical  substances  are  returned  to  the  soil  and  air  to 
be  used  again  by  other  living  things. 

QUESTIONS 

What  are  the  most  important  things  that  the  grasshopper  must  do  to 
live  ? 

How  is  the  grasshopper  protected  ?  How  does  the  grasshopper  breathe? 
How  get  its  food  ? 

How  does  the  grasshopper  begin  life  ? 

Define  metamorphosis.  How  many  kinds  of  metamorphosis  are  there? 
Which  kind  does  the  grasshopper  show  ? 

Is  the  grasshopper  a  friend  or  an  enemy  to  man  ?     Why  ? 


*$0&* 


CHAPTER   II 


OTHEE  COMMON  INSECTS 

In  the  preceding  chapter  we  studied  the  grasshopper,  a 
typical  member  of  the  Orthoptera.  We  shall  now  take  up 
several  other  orders  of  insects,  with  most  of  which  we  are 
already  familiar. 

15.  Hemiptera.  —  Another  common  order  of  insects  is 
the  Hemiptera   (he-mip'ter-a:    Greek,  hemi,  half;  pteron, 


Figure   17. —  Scale  Insects  on  Fern. 

wing).  To  this  order  belong  such  common  insects  as 
the  cicadas,  plant  lice,  the  woolly  aphis,  and  the  bane  of 
the  orchard,  the  San  Jose  (san  ho-sa')  scale.  Some  of 
these  are  very  harmful.  When  the  San  Jose  scale  is 
allowed  to  feed  freely,  whole  orchards  may  be  destroyed. 
Plant  lice  injure   apple,  cherry,  and  peach  trees,  and  the 

24 


CICADA 


25 


Figure  18.  —  Mealy  Bug. 
One  of  the  scale  insects. 


cabbage  plant.  The  several  kinds  of  scale  insects  which 
harm  orchards  may  be  killed  by  spraying  the  trees  with  a 
solution  of  lime  and  sulphur. 

16.  Cicada.  —  One  of  the  most  interesting  insects  of  the 
Hemiptera  is  the  seventeen  year  cicada  (si-ka/da),  com- 
monly called  the  "  seventeen 
year  locust."  The  name  is 
given  to  it  because  the 
nymphs  (nim'fs,  the  imma- 
ture stage)  remain  in  the 
ground,  actively  feeding  on 
roots,  for  seventeen  years. 
There  is  another  kind  of 
cicada  that  remains  in  the 
ground  for  thirteen  years. 

Every  thirteen  or  seven- 
teen years,  generally  in  the 
month  of  May,  the  nymphs  crawl  out  of  the  ground,  climb 
trees  or  fences,  and  molt  into  adult  cicadas.  The  adult 
females  lay  their  eggs  in  tender  shoots  of  trees,  and  this 
causes  the  shoots  to  die.  The  young  cicadas,  after  hatch- 
ing in  the  shoot  of  the 
tree,  go  into  the  ground 
and  begin  their  long 
period  of  larval  exist- 
ence which  lasts  thirteen 
or  seventeen  years. 
These  cicadas  are  usu- 
ally found  in  limited 
areas,  but  in  these  areas 

Figure  19. -Cicada,  Adult  and  Nymph.      are  very  numerous. 

The  cicadas  which  we 
hear  every  summer  are  another  kind,  whose  nymph  lives 
in  the   ground  for  two  years.     As  there  are  two  broods 


26 


OTHER   COMMON  INSECTS 


of  this  species  that  appear  in  alternate  years,  the  number 
does  not  seem  to  vary  from  year  to  year.  The  birds  do 
much  towards  destroying  them.     The  kingbird,  sparrow 

hawk,  butcher  bird,  and 
great-crested  flycatcher 
are  their  most  common 
enemies. 

17.  Coleoptera.  —  The 
Coleoptera  (co-le-op'- 
ter-a  :  Greek  coleos, 
shield  ;  pteron,  wing) 
are  the  beetles.  The 
first  pair  of  wings  is 
horny  and  meets  in  a 
The  second  pair  of  wings 
The  mouth  parts  are  for 


Figure  20.  —  May  Beetle. 

Note  difference  in  first  and  second 
pairs  of  wings. 


straight  line  down  the  back, 
consists   of    thin   membranes, 
biting.       Among    the   harmful    beetles    are    many    wood 
borers,  the  May  beetles, 
potato  beetles,  asparagus 
beetles,     and      weevils. 
Some   of   the    beneficial 
beetles  are  the  ladybug, 
which  feeds  on  destruc- 
tive and  harmful  insects, 
and  the   carrion  beetle, 
that      feeds      on     dead 
animals. 

The  ladybugs  are 
decidedly  beneficial. 
Their  larvae  run  over 
leaves  and  feed  on  other 
insects.  Even  as  adults  they  continue  this  good  work. 
Hop  growers  appreciate  the  value  of  the  ladybug  larvae  on 
their  vines,  as  the  ladybugs  destroy  the  harmful  hop  lice. 


Figure  21. —  Eggs  of  Ladybug. 


LEPIDOPTERA 


27 


Through  the  investigations  of  the  United  States  I)e- 
partment  of  Agriculture  a  certain  kind  of  ladybug 
(Vedalia)  was  found  in  Australia,  which  is  the  natural 
enemy  of  an  insect  pest  (cottony  cushion  scale)  that  was 
destroying  the  orange  trees  grown  in  California.  This 
scale  is  a  plant  insect  which  was  imported  into  the  I  nited 
States  on  young  trees. 
Being1  freed  from  their 
natural  enemies  (Ve- 
dalia) which  were  not 
imported,  they  had  in- 
creased rapidly.  The 
prompt  importation  of 
Vedalia  put  an  end  to 
their  increase,  and  tliey 
are  now  of  no  great 
economic  importance. 

The  bird  enemies  of 
the  beetle  are  numerous. 
Among  the  most  impor- 
tant are  the  ring-necked 
pheasant  recently  intro- 
duced, the  rose-breasted 
grosbeak,  and  the  quail, 
which  feed  particularly 
on    the   potato   beetles. 

The  English  sparrow,  cuckoo,  and  kingbird  feed  on  the 
weevils.  Robins,  blackbirds,  and  crows  eat  the  white 
grubs,  the  larval  stage  of  the  May  beetles.  The  wood- 
peckers destroy  great  numbers  of  borers  by  digging  holes 
in  the  trees  where  the  borers  are  tunneling. 

18.  Lepidoptera.  —  The  Lepidoptera  (lep-i-dfy/ter-a  : 
Greek,  lepidas,  scaly  ;  pteron,  wing)  include  the  familiar 
moths  and  butterflies.     Some  of  the  members  of  this  order, 


Figure  22. 


Holes  made  by  Wood- 
peckers. 


28 


OTHER   COMMON  INSECTS 


Figure  23. 


-Redheaded  Wood- 
pecker. 


such  as  the  adult  peach-tree 
borer,  look  more  like  wasps 
than  like  moths.  There  are 
more  harmful  insects  in  the 
Lepidoptera  than  in  any  other 
order.  Among  the  particularly 
destructive  members  are  the 
insects  which  are  commonly 
called  codling  moths,  gypsy 
moths,  brown  tail  moths,  tent 
caterpillars,  cut-worms,  army 
worms,  and  canker  worms. 
But  not  all  the  Lepidoptera  * 
the   most   beautiful   moths   and 


are  harmful.  Many  of 
butterflies  develop  from  larvae 
that  do  no  particular  harm.  Their 
natural  enemies,  such  as  birds  and 
ichneumons  (see  section  21,  page 
39),  keep  their  numbers  reduced. 
Among  the  more  strikingly  colored 
butterflies  are  the  black  swallow- 
tail, the  larvse  of  which  feed  on 
celery,  parsley,  and  carrots  ;  and 
the  monarch  or  milkweed  butter- 

fly- 

LABORATORY   STUDY 

The  adult  monarch  butterfly  has  the 
body  divided  into  head,  thorax,  and  ab- 
domen. The  legs  are  smaller  than  in  the 
grasshopper,  while  the  wings  are  larger. 
The  butterfly  is,  therefore,  poorly  adapted 
for  jumping,  but  better  adapted  for  flying 
than  the  grasshopper.     Draw  the  entire  animal.     Draw  wings  and  legs. 

Gently  rub  the  finger  on  the  wing,  and  as  the  dust  comes  off,  the  wing 


Figure   24.  —  Larva  of 
Mourning  Cloak  Moth. 

Gradually  transforming 
into  a  pupa.  The  cast-off 
skeletons  of  the  larva 
appear  in  the  middle  row. 


1  The  Chinese  silkworm  is  a  valuable  member  of  this  order. 


LEPIDOPTERA 


29 


will  look  more  like  the  wing  of  a  fly  or  bee.    The  lines  that  run  length- 
wise of  the  wing  are  the  veins.     Draw  the  winu. 

The  mouth  parts  of  the  butterfly  are  united  into  a  single  long  tube 
which  is  the  coiled  tongue-like  structure,  called  the  proboscis  (pro-bos' is). 
Unroll  it  and  see  how  its  length  compares  with  the  length  of  the  body. 
The  butterfly  uses  the  proboscis  to  suck  nectar  from  flowers. 


Figure  25.  — Transformation  of  Pupa  of  Mourning  Cloak  Butterfly 

into  Adult. 


30 


OTHER   COMMON  INSECTS 


As  the  butterfly  goes  from  flower  to  flower  after  nectar,  its  head  brushes 
against  the  parts  of  the  flower  that  grow  the  pollen  dust.     The  pollen  is 

thus  carried  from  one  flower  to  another, 
and  this  helps  the  flower  to  grow  better 
seeds. 

Enemies  of  the  Lepidojotera.  — 
The  numerous  enemies  of  the 
Lepidoptera  prevent  them  from 
becoming  a  scourge.  Chief 
among  these  enemies  are  the 
ichneumons,  members  of  the 
order  Hymenoptera  (Figure 
40).  Ichneumon-  (lk-nu'mon) 
adults  lay  their  eggs  on  the 
bodies  of  many  caterpillars. 
When    these    eggs    hatch    into 


Figure  26. —  Cecropia  Moth. 

Larva,  pupa,  cocoon,  and 
adult. 


Figure  27.  —  Young  Tobacco  Worm. 
Bearing  cocoons  of  parasite. 


small  larvae  ichneumons,  the  larvse  eat  their  way  into  the 
body  of  the  large  caterpillar,  where  they  live  feeding  upon 
its  body  juices.     These  ichneumon  larvse  are  called  para- 


Charles  Robert  Darwin  (1809-1882).  the  celebrated  English 
naturalist,  was  the  founder  of  the  Darwinian  theory  of  evolution. 

After  taking  part  in  the  scientific  expedition  of  the  Beagle  around 
the  world,  Darwin  settled  in  1842  in  the  secluded  village  of  Down 
in  Kent,  where  he  devoted  himself  to  a  life  of  study  and  scien- 
tific research.  In  1859  he  published  his  chief  work.  "The  Origin 
of  Species,"  which  was  translated  into  many  languages  and  be- 
came the  subject  of  more  discussion  than  any  volume  of  the  age. 
A  second  great  work,  "The  Descent  of  Man,"  appeared  in  1871. 
and  Darwin  continued  to  produce  important  scientific  works 
throughout  his  life. 


LEPIDOPTERA 


31 


sites  because  they  derive  their  food  from  the  caterpillar. 
The  caterpillar  which  contains  these  ichneumon  parasites 
is  called  a  host. 

The  ichneumon  parasitic  larva3  grow  rapidly  and  before 
the  caterpillar  dies  they  reach  the  stage  at  which  they 
turn  into  pupse.  When  they  are  ready  to  pupate,  they  eat 
their  way  out  of  the  body 
3f  the  caterpillar  and 
spin  a  cocoon  which  in 
some  cases  remains  at- 
tached to  the  body  of  the 
3aterpillar  (Figure  27). 
These  parasitic  larvae  so 
veaken  the  caterpillar 
:hat  it  dies.  We  shall 
earn  more  of  these  ich- 
leumons  later. 

Next  to  ichneumons, 
she  birds  are  probably 
:lie  most  active  enemies 
>f  the  Lepidoptera. 
Many  birds  live  entirely 
ipon  caterpillars  and  we 

ind  birds  that  seek  them  as  food  in  all  stages  of  their 
levelopment  and  growth.  The  eggs  laid  on  the  twigs 
md  trunks  of  trees  are  eaten  by  chickadees,  nuthatches, 
Drown  creepers,  and  woodpeckers.  The  larva'  are  eaten 
3y  many  birds,  notably  by  cuckoos,  bluebirds,  wrens. 
blackbirds,  orioles,  blue  jays,  crows,  and  house  sparrows. 
The  cocoons  and  pupae  are  sought  by  the  chickadees, 
woodpeckers,  nuthatches,  and  brown  creepers.  The  adult 
nsects  are  preyed  upon  by  house  sparrows,  chipping 
sparrows,  and  the  whole  group  of  flycatchers,  including 
:he  kingbirds  and  phoebes. 


Figure  28.  —  Larwe  of  a  Leaf  Miner. 
At  work  in  an  elm  leaf. 


32 


OTHER   COMMON  INSECTS 


19.    Codling    Moth. — 

The  most  destructive 
of  the  lepidopterous 
insects  is  the  codling 
moth,  already  men- 
tioned as  an  example  of 
metamorphosis.  The 
larvre  become  adult  in 
April  at  about  the  time 
the  early  apple  trees 
blossom.  The  eggs  are 
laid  on  the  young  apples 
and  the  larvse  begin  to 
eat  the  growing  apple, 
which,  as  a  result,  in 
many  cases  drops  to  the 
ground.  In  any  event 
the  quality  of  the  apple 
is  injured. 
In  most  parts  of  our  country,  there   are   two  distinct 

broods  of  the  codling  moth,  the  life  history  of  which  has 

only  recently  been  clearly  understood.     The  eggs  of  the 

second    brood    are   laid 

generally     in      August 

when  the  fruit  is  pretty 

well     grown.         The 

same  damage  is  done  as 

to  the  early  apples,  but 

as   each  mature    female 

lays  a  hundred  or  more 

eggs   and   as   the    most 

important  apple  crop  is 

the  late   one,   the   chief 

damage  is  at  this  time.  Figure  30.  —  A  Geometrid  Moth. 


Figure  29. —  Cedar  Bird. 

Feeding  its  young  a  flying  insect.     One 
of  our  most  beneficial  birds. 


CODLING   MOTH 


33 


It  was  estimated  that 
in  1898  the  injury  done 
by  the  codling  moth  to 
the  apple  and  pear  in- 
dustry in  New  York 
State  alone  amounted  to 
$3,000,000.  By  apply- 
ing a  spray  containing 
some  poison  just  after 
the  blossoms  have  fallen, 
the  codling  moths  may 
be  destroyed.  The  spray 
should  not  be  used  while 
the  blossoms  are  fresh, 
because  then  the  help- 
ful bees  which  visit  them 
are  killed,  and  no  harm 
is  done  to  the  destructive  codling  moths  that  come  later.1 


Figure  31.  —  Protective  Coloration. 


Figure  32.  —  Yellow  Swallowtail. 
Gathering  honey  from  lilacs. 


FIELD,  LABORATORY,  OR 
HOME  STUDY  OF  MOTH S 
AND  BUTTERFLIES 

These  insects  are  easily 
collected  and  are  interesting 
to  study.  From  late  in  the 
spring  until  October  you  can 
find  lame  and  pupa?.  Some 
of  the  leaves  upon  which  the 
larvae  are  feeding  should  be 
collected.  The  larva1  should 
be  placed  in  jars  provided  with 
soil  and  some  leaves.  Arrange 
the  cocoons  and  pupa?  which 
you  find  as  suggested  in  tin- 
following  table. 


1  The  life  history  of  the  peach-tree  borer  and  monarch  butterfly  may  be 

assigned  in  this  connection. 


34 


OTHER   COMMON  INSECTS 


Cocoon 

Pupa 

Spun  with 
silk  only 

Spun  with 
a  leaf 

Spun  with 
hair 

Without 
cocoon 

Suspended 
from  one  end 

Suspended 
from  one  loop 

Parasit- 
ized 

Tent  caterpillars  spin  cocoons  and  form  small  brown  moths.  Celery 
"worms"  hang  in  a  loop  and  form  a  black,  swallowtail  butterfly  which 
feeds  on  the  nectar  of  lilacs  and  the  rhododendrons  of  city  parks. 

The  black  spiny  caterpillars  of  the  willows  and  elms  hang  free  from  the 
knot  of  silk  and  form  the  mourning  cloak  butterfly. 

Tomato  "worms"  burrow  into  the  ground  and  form  a  large-bodied, 
small-winged  moth,  a  sphinx  moth. 

20.  Hymenoptera  —  The  Honeybee. — In  contrast  to  the 
Lepidoptera,  which,  as  has  been  said,  are  probably  the  most 


****» 


6 


Figure  33. — 


a,   Honey  Bee  Worker  ;    b,  Queen  ;    c,  Drone. 
Twice  natural  size. 


destructive  order,  we  find  the  Hymenoptera  (hy-men-op'- 
ter-a:  Greek,  hymenos,  membrane  or  thin  skin;  pteron, 
wing)  that  are  of  the  greatest  value  to  man.  This  order 
includes  the  bees,  wasps,  ants,  ichneumons,  and  the  like. 


HYMENOPTERA  —  THE  HONEYBEE 


35 


Figure  34.  —  1  href. 

Queen  Cells. 

Natural  size. 


The  honeybee  and  the  bumble  bee  are 

the  most  important  of  the  bees.     The 

honeybee  is  valuable  for  its  honey  and 

wax,  and  as  a  distributor  of  the  pollen 

which  is  necessary   for  the   growth  of 

new  plants.    The  bumble  bee  is  valuable 

mainly  as  a  distributor  of  pollen. 

Honeybees  afford  a  splendid  example 

of  community  life  among  insects.     In 

the  wild    state  they  live   in  trees  and 

caves.      All    wild    honeybees    in    this 

country   have    escaped    from    hives    or 

apiaries  (bee  farms). 

In  a  honeybee  colony  there  are  three  classes  of  bees,  — 

the  perfect  females  or  queens, 
the  males  or  drones,  and  the 
imperfect  females,  or  workers. 
There  are  generally  one  queen, 
a  few  hundred  drones,  and  twen- 
ty to  fifty  thousand  workers. 

The  queen  alone  can  lay 
eggs.  She  can  lay  an  unfer- 
tilized egg  which  hatches  into 
a  drone,  or  she  can  lay  an  egg 
which  is  fertilized.  This  fer- 
tilized egg  hatches  into  a  queen 
or  a  worker,  according  to  the 
food  and  the  size  of  the  cell 
which  are  provided  by  the 
workers.  Thus  the  decision 
as  to  whether  the  young  bee 
shall  be  a  queen  or  a  worker 

rests  with  the  workers  themselves.     They  also  have  t lie 

power  to  supersede  the  queen,  or  to  raise  a  new  queen 


Figure  35.  —  a,  Honey  Bee 
Egg;  b,  Young  Larva;  c,  Old 
Larva  ;    d,  Pupa. 

Three  times  natural  size. 


36 


OTHER   COMMON  INSECTS 


in  case  of  the  sudden  death  of  the  old  one.  These  powers 
are  rightly  intrusted  to  the  workers — the  great  majority. 
The  eggs  are  placed  by  the  queen  in  cells,  and,  after 
hatching,  are  fed  by  the  young  workers,  called  nurses. 
The  larva  is  fairly  bathed  in  food.     In  a  few  days  the 

larva  is  full  grown,  and 
then  pupates.  The 
workers  now  cap  over 
the  cell  with  wax,  and 
in  about  twenty-one  days 
the  young  bee  cuts  away 
the  cap  and  crawls  out 
— an  adult  provided  with 
four  wings,  mouth  parts, 
antennae,  and  the  six  legs 
of  the  honeybee. 

Workers  are  provided 
with  the  sting  which  is  a 
weapon  of  both  defense 
and  offense.  The  queen 
has  a  small  sting,  and 
the  drones  have  none. 
When  bees  sting  large 
animals,  like  men,  horses, 
and  dogs,  their  sting  is 
pulled  out  and  with  it 
parts  of  the  internal  or- 
gans, thus  causing  the  death  of  the  bee.  When  bees  sting 
other  insects,  or  even  one  another,  their  sting  is  not  lost. 

Sometimes  swarms  which  have  few  bees  and  little  honey 
are  attacked  by  bees  from  other  colonies.  It  is  a  pitched 
battle  until  the  "  robber  bees  "  are  beaten  back,  or  the  de- 
fenders are  themselves  killed.  The  sting  is  used  in  these 
battles. 


Figure  36.  —  Honey  Bees  Clustering 
at  Swarming  Time. 


HYMENOPTERA  —  THE   HONEYBEE 


37 


Bees  are  instinctively  sanitary.  If  a  large  bumble  bee 
enters  the  hive,  the  bees  kill  the  intruder  and  usually, 
finding  him  too  large  to  be  taken  out,  embalm  him  by  in- 
jecting the  sting  repeatedly  into  his  body.  The  result  of 
this  operation  is  to  make 
the  bumble  bee  harmless 
to  the  colony.  Some- 
times they  cover  the 
body  of  a  small,  dead 
animal  with  a  case  made 
of  propolis  (prop'6-lis), 
a  substance  the  bees 
gather  from  certain 
buds.  This  serves  to 
protect  the  colony  from 
the  effects  of  the  decom- 
position of  the  body. 

At  irregular  intervals 
during  the  ea/ly  spring 
and  summer,  bees  have 
the  peculiar  habit  of 
swarming.  Several  rea- 
sons for  swarming  are 
given  by  bee-keepers, 
but  no  one  pretends  to 
be  certain  that  he  really 
knows  the  cause.  It  is  a  sort  of  revolt  of  the  bees  against 
their  condition.  Two  of  the  commonest  reasons  given  to 
explain  swarming  are  the  lack  of  room  for  the  growing 
colony,  and  lack  of  food. 

When  bees  swarm,  they  usually  light  on  the  limb  of  a 
tree  and  form  a  dense  cluster.  Here  they  hang  from 
fifteen  minutes  to  an  hour  before  leaving  for  the  woods. 
In  a  few  cases  bees  have  remained  in  this  "cluster"  state 


Figure  37. —  Capturing  a  Swarm. 


38 


OTHER   COMMON  INSECTS 


overnight,  but  usually  they  are  lost  unless  they  are  col- 
lected inside  of  half  an  hour.  The  swarm  consists  of  a 
large  number  of  adult  bees,  workers  and  drones,  and 
usually  a  single  queen. 

Various  devices  against  swarming  have  been  invented, 
but  the  most  effective  is  to  clip  the  wings  of  the  queen 
in  order  that  she  may  be  kept  at  home,  because  the  other 


Figure  38.  —  Model  Apiary. 


bees  usually  follow  her.  This  is  done  after  the  queen  has 
taken  her  "  wedding-flight."  Her  wings  are  clipped  close 
to  the  body,  but  only  on  one  side.  The  bees  that  then 
swarm  soon  come  back  and  are  easily  controlled.  While 
the  bees  are  still  in  the  air,  a  clean,  empty  hive  is  placed 
where  the  old  one  was.  Beekeepers,  during  the  swarm- 
ing period,  always  have  a  number  of  empty  hives  in  position 
ready  for  the  swarm  to  occupy. 

The  returning  bees  enter  the  new  hive  in  search  of  the 
queen.     As  they  are  rushing  in,  the  queen  with  clipped 


HYMENOPTERA  —  THE   HONEYBEE 


39 


wings  is  released,  and  she,  in  turn,  joins  the  procession 

and  enters  with  the  others.      Having  found  the  queen  and 

plenty  of  room,  the  colony  is  usually  content  to  remain. 

Sometimes  swarming  becomes  a  mania  with  certain  colonics, 

and  it  is  difficult  to  get  them  to  settle  down  contentedly  in 

a  hive  and  make  honey. 

Runaway    swarms    have 

to  be  watched  with  great 

patience.    Bees  that  have 

been  raised  for  many  bee 

generations  in  man-made 

hives    sometimes     leave 

suddenly  and  seek  out  a 

hollow  tree  in  the  forests. 

The  length  of  the  bee's 
life  varies.  The  drones 
are  usually  killed  at  the 
end  of  their  first  season. 
Queens  live  for  five  or 
six  or  even  ten  years. 
Workers    live    three    or 

four  weeks  in  the  working  season  and  several  months  in 
the  fall  or  winter. 

The  honey  and  wax  produced  annually  in  the  United 
States  are  valued  at  122,000,000. 

21.  Ichneumons.  —  Another  interesting  division  of  the 
Hymenoptera  are  the  ichneumons.  We  have  already  seen 
(page  30)  how  they  help  to  keep  the  Lepidoptera  from  be- 
coming a  scourge.  They  also  furnish  other  interesting  ex- 
amples of  parasitism.  As  an  illustration  Ave  may  use  one 
of  the  larger  ones  known  as  Tfialessa.  With  long,  thread- 
like drills  this  parasitic  insect  bores  holes  in  trees,  and  lavs 
an  egg  at  the  bottom  of  the  hole.  The  egg  is  usually  laid 
near  the  burrow  of  one  of  the  larger  tree  borers,  the  Tremex* 


Figure  39.  —  Cutting  Combs  from 
Box  Hive. 


40 


OTHER   COMMON  INSECTS 


The  larva  of  the 
Thalessa  makes  its  way 
along  the  burrow  of  the 
Tremex  borer  and  fas- 
tens itself  to  the  body  of 
the  borer,  where  it  feeds 
upon  the  borer  and  thus 
kills  it.  In  time  the 
adult  Thalessa  emerges, 
ready  in  turn  to  do  its 
part  in  laying  eggs 
which  will  destroy  more 
of  these  enemies  of  the 
tree.  But  if  the  Thalessa 
parasites  kill  the  Tremex 

borer  before  it  has  eaten 

Figure  40.  —  Ichneumon   Flies.  .,  ,-,  ■,     . ,      *        n 

its  way  through  the  hard 
Laying  eggs  in  a  tree.  ,        .  n      ,. 

wood,    then    all    die  to- 
gether, because  the  Thalessa  cannot  cut  an  opening  for  itself. 


Figure  41.  —  Adult  Horn-tailed  Saw-fly. 

Just  after  laying  eggs  in  a  tree.     The  larvae  of  this 
insect  do  much  damage  to  lumber. 


DIPTERA 


41 


22.  Ants.  —  The  ants  are  insects  which  live  in  large 
families.  Each  family  has  many  workers,  and  a  number 
of  queens  and  males.  Certain  kinds  have  in  addition  their 
soldiers  which  have  strong  mouth  parts  (mandibles).  The 
soldiers  do  the  fighting  for  the  family.  Some  ants  are 
winged  and  others  are  wingless. 

Many  ants  have  the  curious  habit  of  protecting  the  plant 
lice,  because  these  lice  give  off  a  sweet  fluid  of  which  the 
ants  are  fond.  In  some  cases  the  ants  carry  the  plant  lice 
from  the  wilted  leaf  to  a  fresh  one,  or  confine  them  in  the 
ants'  nest  and  bring  them  fresh  leaves.  When  they  wish 
to  feed  on  the  sweet  fluid,  the  ants  quietly  stroke  the  body 
of  the  plant  lice  with  their  antennae. 

23.  Diptera. — The  Diptera  (dip'ter-a:  Greek,  dia,  two; 
pteron,  wing)  include  such  harmful  insects  as  the  mos- 
quito, housefly,  botfly,  and 
cheese  skipper  ;  also  the  bene- 
ficial bee  fly,  wasp  fly,  and 
tachina  fly. 

The  most  important  member 
of  this  group  is  the  mosquito. 
The  common  mosquito  lays  its 
eggs  in  the  water  in  small  clus- 
ters which  look  like  minute 
rafts.  These  eggs  hatch  into 
larvse,  called  "  wigglers. "  Any 
stagnant  pool  or  rainwater  bar- 
rel furnishes  a  favorable  place  for  mosquitoes  to  breed. 

In  the  United  States  there  are  three  distinct  kinds  of 
mosquitoes.  (1)  The  common  mosquito  is  known  by  the 
technical  name  of  Culex  (kiVleks).  It  is  not  known  that 
the  Culex  carries  in  its  body  any  disease  germs  harmful 
to  men,  therefore  it  is  regarded  as  harmless,  although  a 
source  of  great  annoyance  to  those  who  frequent  the  woods 


Figure  42.  —  Fly. 


42 


OTHER   COMMON  INSECTS 


a 

I 


- 


-  *  ' 


'       ■!, 


It 

if  ft 


\a>. 


3;-    - 


Figure  43.  —  Eggs  and  Larwe  of 

CULEX. 

The  commonest  mosquito. 


or  seashore  during  the 
summer.  (2)  Anopheles 
(a-nof7 e-lez)  is  the  scien- 
tific name  of  a  second 
kind  of  mosquito,  which 
is  also  generally  distrib- 
uted, but  is  not  so 
numerous  as  the  Culex. 
The  Anopheles  often 
carries  in  its  body  the 
germs  that  cause  the 
disease    called    malaria. 


(3)  Stegomyia  (steg-o-mi'ya)  is  a  mosquito  common  in  the 
southern  part  of  the  United  States.  It  is  the  insect 
which  carries  the  germs  of  yellow  fever  from  one  person 
to  another. 

It  is  fortunate  that  the  mosqui- 
toes have  so  many  enemies.  The 
"  wigglers  "  are  preyed  upon  by  the 
larvas  of  the  dragon  flies,  by  small 
fish,  and  by  water  beetles;  while 
the  adults  are  eaten  by  nighthawks, 
martins,  bats,  and  dragon  flies. 
Certain  diseases  caused  by  plants 
attack  the  adults  and  kill  them  in 
great  numbers.  The  number  of 
mosquitoes  can  be  greatly  reduced 
by  destrojdng  their  natural  breeding 
places  in  old  rain  barrels,  watering 
troughs,  boxes  that  may  hold  water, 
pails,  eaves  troughs,  and  sink  holes. 
The  larger  breeding  places  are 
sluggish  streams  and  swamps. 
Draining  these  is  the  most  effective 


Figure  44.  —  a,  Adult 
Culex  ;  b,  Adult 
Anopheles. 


SUMMARY  43 

method  of  preventing  mosquitoes  from  laying  their  eggs 
in  that  locality.  When  this  is  not  possible,  the  surface 
of  the  water  may  be  covered  with  kerosene,  which  kills 
the  larvce  by  preventing  them  from  getting  oxygen  from 
the  air.  Frequent  applications  of  oil  greatly  reduce  the 
number  of  mosquitoes. 

SUMMARY 

The  insects  include  a  large  number  of  animals,  the 
smallest  of  which  can  be  seen  only  through  a  microscope, 
while  the  largest,  certain  butterflies,  measure  nine  inches 
across  their  wings.  S.ome  insects  are  parasitic  and  lead 
dependent  lives.  Insects  feeding  on  plants  which  we 
wish  to  eat  are  called  harmful.  Others,  like  the  honey- 
bees and  silkworms,  which  make  products  that  we  use, 
are  beneficial.  Insects  such  as  ticks  and  lice,  that  injure 
our  domestic  animals,  are  called  harmful.  Then  there 
are  the  beautifully  colored  moths  and  butterflies  whose 
larvre  never  become  numerous  enough  to  do  much  damage  ; 
we  say  that  they  are  beneficial  because  we  get  pleasure 
from  their  beauty. 

The  whole  question  of  what  is  beneficial  or  harmful 
depends  on  the  relation  of  the  insect  to  man.  Insects 
living  on  an  uninhabited  island  could  not  be  thus  classi- 
fied. In  the  earlier  stages  of  our  civilization,  many  insects 
now  regarded  as  harmful  were  not  so  classified,  because 
man  had  not  learned  to  use  the  plants  upon  which  they 
fed.  The  important  relation  which  insects  bear  to  disease 
has,  in  recent  years,  caused  us  to  classify  several  insects 
as  harmful  which  were  not  so  considered  earlier. 

Insects,  like  man,  are  constantly  undergoing  a  struggle 
to  escape  their  enemies  and  to  secure  food  and  a  place  to 
live.  It  is  interesting  in  this  biological  study  to  try  to 
view  ourselves  in  the  same   unprejudiced  way  in  which 


44  OTHER   COMMON  INSECTS 

we  study  the  lower  animals ;  it  helps  us  better  to  under- 
stand ourselves,  and  to  go  forth  better  equipped  to  wage 
our  contest  and  win  our  fight. 

QUESTIONS 

Explain  the  difference  between  beneficial  and  injurious  insects. 
Which  are  some  of  our  most  beneficial  insects  ?     How  do  they  help 
us? 

How  did  they  help  to  save  the  orange  industry  of  California  ? 

How  do  fruit  growers  spray  their  trees  ?     Why  ? 

What  can  you  do  to  prevent  harmful  insects  from  spreading  ? 

KEFERENCES 

Crary,  Field  Zoology,  Chapter  X. 

Folsom,  Entomology  with  Reference  to  Its  Biological  and  Economic 
Aspects. 

Hegner,  Introduction  to  Zoology,  Chapter  XII. 
Hodge,  Nature  Study  and  Life,  Chapter  X. 
Kellogg,  Animals  and  Man,  Chapter  XV. 
Osborne,  Economic  Zoology,  Chapter  XII. 
Root,  A.  B.  C.  and  X.  Y.  Z.  of  Bee  Culture. 
Smith,  Our  Insect  Friends  and  Enemies. 


CHAPTER    III 

THE   SIMPLEST   ANIMALS  — PROTOZOA 

24.  Definitions. — In  our  study  of  the  grasshopper  and 
its  insect  relatives  we  considered  their  behavior  and  life 
processes.  If  we  had  studied  the  minute  structure  of  any 
of  these  insects,  the  grasshopper,  for  example,  and  had 
used  a  microscope  to  aid  us,  we  should  have  found  that 
every  organ  was  made  up  of  numerous  small  parts  joined 
together  in  a  definite  manner.  These  small  parts  are 
called  cells. 

Any  book  on  biology  uses  the  word  cell  again  and  again. 
The  name  was  first  used  by  Robert  Hooke  over  two  hun- 
dred years  ago,  when,  with  his  crude  microscope,  he 
examined  a  piece  of  bark  and  found  it  to  be  made  up  of 
little  rooms  which  looked  like  the  cells  of  the  honey  com  I). 
These  spaces  he  named  cells.  When  better  microscopes 
were  made,  the  living  parts  of  the  cell  were  discovered, 
and  it  was  found  that  Hooke  had  seen  only  the  walls  of 
dead  cells. 

All  plants  and  animals  are  composed  of  cells.  A  cell 
may  exist  alone,  carrying  on  all  the  life  processes  itself, 
or  it  may  exist  in  connection  with  a  great  many  other 
cells,  as  in  all  large  animals  and  plants.  In  every  case 
each  cell  is  produced  from  another  cell. 

There  are  certain  animals  that  are  never  more  than  one- 
celled  even  when  they  are  full  grown.  These  animals  are 
called  Protozoa  (pro-to-zd'a:  Greek,  protos,  first;  zoon, 
animal). 

45 


46  THE  SIMPLEST   ANIMALS  —  PROTOZOA 

25.  The  Protozoan  Cell.  —  The  protozoan  cell  is  a  single 
mass  of  living  matter,  called  protoplasm.  In  a  general  way 
it  carries  on  the  same  life  processes  as  the  grasshopper;  or 
any  other  animal.  When  this  living  cell  comes  in  con- 
tact with  heat,  cold,  electricity,  chemicals,  or  other  stimuli, 
it  moves,  and  we  say  that  it  is  irritable.  The  term  irrita- 
bility, used  with  a  scientific  meaning,  is  defined  as  the  power 
of  being  aware  of  a  stimulus.  When  this  living  cell  is 
brought  into  contact  with  cold,  for  example,  it  makes  a 
definite  movement.     It  is  aware  of  the  cold  stimulus. 

The .  living  cell  grows  by  using  food.  It  takes  in  oxy- 
gen from  the  water  or  from  the  air,  according  to  where  it 
happens  to  live.  It  gives  off  waste  substances.  It  can 
grow  or  reproduce  other  cells  of  the  same  kind. 

Many  protozoan  cells  have  no  limiting  wall  between 
the  living  substance  and  the  water  in  which  they  live. 
Yet  the  protoplasm  and  the  water  do  not  mix,  though  we 
do  not  understand  why.  Other  Protozoa  living  in  the 
ocean  are  surrounded  by  extremely  thin  skeletons  of  lime, 
and  when  the  animals  die  their  skeletons  sink  to  the  bot- 
tom and  become  massed  in  a  sort  of  rock.  The  famous 
chalk  cliffs  of  England  were  formed  in  this  way. 

26.  Habitat.  —  The  habitat  of  any  animal  is  the  place 
where  it  lives.  The  Protozoa  are  small,  usually  micro- 
scopic, animals  common  in  stagnant  pools  and  in  swamp 
water.  They  are  also  common  in  salt  water.  In  fact, 
Protozoa  are  likely  to  be  found  in  nearly  all  ponds  of 
water  that  contain  food  for  them.  Often,  in  the  summer 
time,  our  attention  is  called  to  the  activities  of  Protozoa 
when  the  water  from  lakes  or  reservoirs  has  a  fishy  taste. 
This  peculiar  taste  may  be  due  either  to  animals  or  plants, 
or  to  both.  When  it  is  due  to  animals,  it  is  caused  by  a 
disagreeable  oil  formed  by  a  certain  kind  of  Protozoa. 

By  far  the  greater  number  of   Protozoa  are  harmless, 


STRUCTURE   OF   AMCEBA 


47 


and  many  arte  helpful  to  us  in  that  they  serve  as  food  for 
fishes.  Others,  however,  may  become  parasitic  in  our 
bodies,  and  thus  cause  such  diseases  as  malaria,  yellow 
fever,  or  sleeping  sickness. 

27.  Amoeba. — The  name  amoeba  (a-me'ba)  is  given  to 
several  different  Protozoa,  but  all  of  them  represent  the 
simplest  form  of  life  known  to  us.  For  this  reason  they 
are  always  studied  in  biology.  In  order  to  describe  cor- 
rectly the  structure  of  even  so  simple  an  animal  as  the 
amoeba  a  few  new  words  are  necessary. 

28.  Structure  of  Amoeba.  —  It  is  difficult  for  inexperienced 
students  to  see  the  living  amceba  through  the  microscope, 
because    the   whole    cell 

has  a  faint,  grayish  ap- 
pearance, and  in  a  strong 
light  is  transparent. 
But  if  this  grayish  ap- 
pearance of  protoplasm 
is  once  seen,  it  is  always 
remembered. 

The  living  amoeba  is 
continually  changing 
shape  and  pushing  out 
from  the  surface  of  its 
body  blunt,  finger-like 
projections  of  the  proto- 
plasm called  pseudopodia 

(su-do-po'dl-a:  Greek,  pseudo,  false;  pod,  root  of  pons. 
foot),  which  give  an  irregular  outline  to  the  body  (Figure 
45).  Sometimes  the  pseudopodia  branch  out,  and  there- 
fore the  scientific  name  Rhizopoda  (ri-zop'o-da:  Greek, 
rhizos,  root;  pod,  root  of  pous,  foot)  is  the  technical 
name  for  all  amoeba-like  Protozoa. 

The  amoeba  sends  out  a  pseudopodium,  and  gradually 


Figure  45.  —  Micro-photograph  of  an 
Amceba. 


48  THE  SIMPLEST  ANIMALS  —  PROTOZOA 

the  rest  of  the  body  flows,  by  a  rolling  movement,  in  the 
same  direction.  This  creeping-rolling  motion  of  the 
protoplasm  enables  the  amoeba  to  move  through  the  water. 
When  the  pseudopodium  comes  in  contact  with  a  minute 
plant  upon  which  the  amoeba  feeds,  the  protoplasm  of  the 
pseudopodium  surrounds  the  plant  and  takes  it  into  the 
cell.  The  microscopic  plant  thus  eaten  by  the  amoeba  is  in- 
closed, with  a  small  amount  of  water,  in  a  tiny  globe  called 
the  food  vacuole  (vak'u-ol).  The  food  vacuole  is  to  be 
thought  of  as  a  stomach  in  which  digestion  can  take  place, 
for  the  plant  is  digested  in  it.     The  nutritious  parts  are 

absorbed  into  the  proto- 
plasm, the  undigested 
parts  are  cast  from  the 
cell,  and  the  food  vacuole 
disappears. 

There     is      no     well- 
defined  cell  wall  ;  there- 


Feelmg  pseudopodium. 
Ectoplasm 
Endopldsm  /      \ 


£» 


Nucleus  ; 

Walking  pseudopodium 


Figure  46.  —  Diagram  of  an  Amceba.       f ore     the    amoeba     IS    an 

illustration  of  a  living, 
naked  cell.  Near  the  center  of  the  cell  is  a  spherical 
mass  of  denser  protoplasm  called  the  nucleus.  In  many 
amoebaB  the  nucleus  is  not  easily  seen  except  by  means 
of  specially  stained  preparations.  The  rest  of  the  proto- 
plasm in  the  cell  is  called  cytoplasm  (si'to-plazm).  This 
does  not  appear  the  same  in  all  parts  of  the  amoeba.  On 
the  outside,  there  is  a  thin,  almost  transparent  layer, 
called  ectoplasm  (ek'to-plazm  :  Greek,  ecto,  outside; 
plasma,  form).  The  larger  part  of  the  cytoplasm  is  filled 
with  numerous  small  granules  and  contains  several 
vacuoles.  This  inner  mass  of  cytoplasm  is  called  endo- 
plasm  (en'do-plazm:  Greek,  endo,  within;  plasma,  form). 
The  vacuoles  in  the  endoplasm  may  contain  food,  water, 
or  waste   products.     The   food  and   water  vacuoles   are 


REPRODUCTION  AND  ENCYSTMENT  49 

temporary  structures,  but  the  vacuole  which  collects 
the  liquid  waste  is  always  present.  When  this  vacuole 
reaches  full  size,  it  suddenly  contracts  and  throws  the 
waste  into  the  water.  This  excretory  vacuole  is  therefore 
called  the  contractile  vacuole.1 

29.  Respiration.  —  The  amoeba  respires.  From  the  air 
dissolved  in  the  water,  it  obtains  by  diffusion  the  oxygen 
necessary  to  its  life,  and  it  gives  off  carbon  dioxide  from 
the  cell. 

30.  Reproduction  and  Encystment.  —  The  chief  method  of 
reproduction  in  the  amoeba  is  simple  (Figure  47 J.  The 
living  cell  divides  into  two 
equal  parts,  forming  two  new 
cells.  This  process  is  known 
as  fission  (fish'un  :  Latin,  fissus, 
cleft). 

When  the  food  or  water  be- 
comes  unsuited   to  supply  the      _  Am      A  □ 

rr  J  Figure  47.  —  Amceba  Repro- 

needs   of   the   cell,   in   order  to  ducing  by  Fission. 

live    the   amoeba   often   secretes 

(makes  for  itself)  a  thick  wall   completely  surrounding 

the  protoplasm.     This  process  is  termed  encystment  (en- 

sist'ment:   Greek,  en,  in  ;  kystis,  bladder).     After  the  wall 

has  been  formed,  the  amoeba  is  able,  for  a  long  period,  to 

resist  cold,  the  drying  up  of  the  pond,  or  the  lack  of  food. 

1  No  suggestion  can  be  made  which  will  always  enable  the  teacher  to  secure 
amoebae.  They  are  more  frequently  found  in  the  slime  and  mud  of  Stagnant 
water  than  anywhere  else.  Paramoecia  and  other  infusoria  can  usually  be 
secured  in  abundance  by  placing  a  handful  of  hay  or  leaves  in  a  jar  and  cov- 
ering them  with  the  ordinary  water  used  in  the  laboratory.  This  is  called  a 
protozoan  culture,  and  should  be  started  about  four  weeks  before  the  material 
is  wanted  for  class  study.  The  length  of  time  that  the  culture  should  stand 
can  be  lessened  by  adding  a  little  beef-extract  and  by  keeping  the  jar  near  a 
radiator.  Water  sufficient  to  keep  the  hay  or  leaves  covered  must  be  added 
from  time  to  time.  When  a  good  culture  of  paramoecia  is  once  secured,  the 
jar  should  be  kept  from  year  to  year,  simply  adding  water  to  the  dried  hay 
left  in  the  jar  wheu  infusoria  are  desired. 


50 


THE  SIMPLEST  ANIMALS  —  PROTOZOA 


31.  Paramecium.  —  One  of  the  most  common  forms  of 
Protozoa  is  the  slipper-shaped  paramcecium  (para-me'- 
shi-um),  which  is  more  active  than  the  amoeba.  It  is 
abundant  in  stagnant  water  and  in  the  hay  infusions  pre- 
pared in  the  laboratory.      (See  Laboratory  Suggestions.) 


LABORATORY   STUDY 

There  are  certain  kinds  of  Protozoa  that  are  usually  found  in  protozoan 
cultures.  The  most  abundant  form  is  the  paramoecium.  Make  repeated 
examinations  of  drops  of  water  from  the  protozoan  culture,  until  you  are 
able  to  find  the  paramoecium.  Notice  its  shape,  rate  of  movement,  be- 
havior on  meeting  obstacles,  and  the  like.  Report  on  what  you  can 
make  out.  Compare  the  paramcecium  with  any  other  protozoan  you  can 
find,  as  to  shape,  rate  of  movement,  size,  color,  etc.  If  available,  ex- 
amine slides  which  show  the  nucleus  of  a  protozoan.  Make  sketches 
that  illustrate  the  above  features. 

32.  Structure  of  Paramcecium.  —  The  paramoecium,  like 
the  amoeba,  is  a  single  cell,  but  it  has  both  a  large  nucleus 

and  a  small  one.     It  has 


0$& 


Contractile.. 
Vacuole 


-L 


•Cilia 


•Cuticle 


Trichocysts 


an  endoplasm,  an  ecto- 
plasm, and  a  cuticle 
(ku'ti-kl),  or  cell  wall. 
Through  the  cuticle, 
there  extend  great  num- 
bers of  cilia  (sil'i-a),  or 
threads  of  living  proto- 
plasm. The  ectoplasm 
contains  many  thread- 
like darts  known  as 
trichocysts  (trlk'o-sists). 
These  can  be  discharged. 
On  one  side  is  a  fold  or 
depression  (the  gullet) 
in  which  food  is  collected  by  the  waving  motion  of  the 
cilia.     Within  the  cell  are  found  food  and  water  vacuoles 


Food 
Vacuole 


•Contractile 
Vacuole 


Figure  48.  —  Diagram  of  Paramcecium. 


REPRODUCTION,   RESPIRATION 


51 


as  in  the  amoeba  ;  but  there  are  two  contractile  vacuoles, 
one  at  either  end,  and  the  food  and  water  vacuoles  are 
more  numerous  than  in  amoeba. 

33.  Locomotion  and  Defense.  —  The  animal  moves  by  the 
action  of  the  cilia,  the  direction  bein^  due  to  the  angle  at 
which  the  cilia  are  held.     It  can 

be  observed  that  the  animals 
move  backward  and  forward, 
and  that  they  also  rotate  on  the 
long  axis.  Paramoecia  defend 
themselves  by  discharging  the 
trichocysts.  This  discharge 
occurs  either  as  a  result  of  cer- 
tain strong  artificial  stimuli, 
such  as  electric  currents  or 
chemicals,  or  naturally  because 
of  collision  with  certain  other 
Protozoa.  If  attacked  by  some 
animal  which  feeds  upon  them, 
they  discharge  the  trichocysts  in  the  region  of  the  attack 
(Figure  49). 

34.  Reproduction,  Respiration.  —  Paramoecia  reproduce  by 
fission,  i.e.,  an  animal  divides,  producing  two;  these 
divide  and    produce    two    more.     The   process  of   fission 

goes  on  indefinitely  (Figure  50).  Like 
the  amoeba  these  forms  can  encyst  win  mi 
conditions  of  life  become  unfavorable. 
They  can  then  be  blown  about  in  dust. 
As  in  amoeba?,  the  oxygen  which  is 
necessary  to  respiration  is  obtained 
from  the  water.  Excretory  waste  is 
cast  from  the   body  by  the  contractile 

vacuoles,  which   force   it  through   the   ectoplasm,      (iases 

escape  from  the  entire  surface. 


Figure  49. —  Paramecium. 

Being  attacked  by  another 
Protozoan  that  feeds  upon 
it.  The  trichocysts  are  dis- 
charged, and  they  force 
the  foe  away. 


Figure  50.  —  Para 
mcecium  reproduc 
ing  by  Fission. 


52 


THE  SIMPLEST  ANIMALS  —  PROTOZOA 


■ 


&S 


35.   Economic  Importance.  —  Paramoecia  consume  consid- 
erable quantities  of  bacteria,  but  whether  more  harmful 

than  helpful  ones  cannot 
be  told.  Therefore  their 
economic  value  is  un- 
certain. 

36.  Other  Protozoa.  — 
If  one  examines  stag- 
nant water,  a  large  num- 
ber of  other  kinds  of 
Protozoa  will  be  found. 
The  more  common  forms 
are  much  like  the  para- 
mcecium  and  have  many 
cilia  on  the  body. 
Several  of  these  large, 
ciliated  Protozoa  feed  on  the  smaller  Protozoa.  Some  of 
the  common  forms  are  shown  in  Figures  51-53. 

All  of  these  various  Protozoa  can  be  grouped  into  classes, 


Figure  51.  —  Vorticella. 


m 


i!S'.-.«.Ji\:-i.v.' 


Figure  52.  —  One  of  the 
foraminfera. 


Figure  53.  —  Some  Flagellate 
Protozoa. 


each  with  certain  distinct  characteristics.     For  instance,  all 
Protozoa  that  have  pseudopodia  are  called  Rhizopoda.     In 


PROTOZOA   AND   ALCOHOL 


53 


this  group,  the  cells  may  be  naked  or  may  possess  a  haul 
mineral  covering ;    a  second  group  of  Protozoa  are  pro- 

• 

vided  with  one  or  more  long,  wavering  threads  called 
flagella  (Ha-jel'la  :  Latin,  flagellum,  whip),  and  have  the 
name  Flagellata ;  the  flagella  are  longer  than  cilia  and 
exhibit  more  complicated  movement.  A  third  class, 
known  as  Infusoria  (in-fu-s<Vri-a),  includes  most  of  the 
common  Protozoa  found  in  protozoan  cultures.  Most  of 
this  class  are  provided  with  cilia. 

LABORATORY   STUDY   OF   PROTOZOA 

Take  a  drop  of  water  from  an  infusion  rich  in  Protozoa ;  place  on 
a  slide  and  examine  with  a  16  mm.  or  J  objective.  Answer  the  questions 
suggested  by  the  report. 


NlMBER    OF 

How  Many  Kinds  — 

How   Many   Kind> 
Have  — 

Kinds 
Observed 

are  free 
swimming  ? 

are  attached 
by  threads? 

have  even 
motion  ': 

have  zigzag 
motion  ? 

constant 
form  ': 

varying 
forma  ! 

37.  Protozoa  and  Alcohol. — Scientists  have  studied  tin- 
relation  of  alcohol  to  the  life  processes  of  Protozoa.  Nor- 
mally, such  Protozoa  as  paramcecia  divide  a  regular 
number  of  times  each  day.  When  a  small  amount  of 
alcohol  is  placed  in  water  containing  paramcecia,  the 
normal  rate  of  fission  is  diminished.  Professor  Wood- 
ruff has  shown  by  an  extended  and  critical  study  that 
alcohol  tends  to  prevent  paramcecia  from  dividing  as 
many  times  as  they  would  under  normal  conditions. 
This  means  that  alcohol  hinders  the  growth  of  paramcecia. 


54  THE  SIMPLEST   ANIMALS  —  PROTOZOA 

SUMMARY 

Protozoa  are  the  simplest  group  of  animals.  They  are 
found  mostly  in  water,  yet  some  are  parasitic  in  higher 
animals.  They  are  small  and  usually  consist  of  only  one 
cell.  They  reproduce  mostly  by  fission.  Some  produce 
in  man  and  beast  diseases,  such  as  malaria  and  the  sleeping 
sickness  of  Africa.  But  the  great  majority  of  Protozoa 
are  not  harmful. 

QUESTIONS 

Compare  the  body  of  a  protozoan  with  the  body  of  a  grasshopper.  In 
what  are  they  alike  ?     In  what  different  ? 

How  do  the  amoeba  and  paramcecinm  compare  ? 

Explain  how  the  Protozoa  eat,  digest  food,  produce  more  Protozoa, 
and  protect  themselves. 

How  do  these  vital  processes  compare  with  the  similar  vital  processes 
in  the  grasshopper  ? 

In  what  ways  are  Protozoa  injurious  to  man  ?     Are  they  parasitic  ? 

REFERENCES 

Galloway,  First  Course  in  Zoology,  Chapter  X. 
Hegner,  Introduction  to  Zoology,  Chapters  IV,  V,  VI. 
Jordan  and  Kellogg,  Animal  Life,  Chapters  II,  III. 
Kellogg,  Animals  and  Man,  Chapter  V. 
Osborne,  Economic  Zoology,  Chapter  II. 


CHAPTER   IV 


THE  SIMPLER  METAZOA 

38.  Metazoa.  —  The  Protozoa  just  studied  are  single, 
free,  living  cells,  while  the  grasshopper  is  made  up  of 
thousands  of  cells.  The  grasshopper  is  called  a  metazoan 
(mSt-a-zo'an  :  Greek,  meta,  after  ;  zoon,  animal)  because 
there  are  many  cells  in  its  body.  The  Protozoa  and  the 
Metazoa  are  alike  in  that  both  take  in  food,  breathe,  give 
off  waste  matter,  and  reproduce  their  kind. 

There  are  a  number  of  organisms  concerning  which 
scientists  disagree  as  to  whether  they  are  plants  or  animals. 
In  zoology,  these  forms 
are  known  as  Colonial 
Protozoa  or  simple  Meta- 
zoa. We  shall  study  two 
of  these  (Gonium  and 
Vol  vox)  and  then  examine 
the  sponges,  which  all 
scientists  agree  are  Meta- 
zoa. 

39.  Gonium.  —  Gonium 
is  an  animal  made  up  of 
sixteen  separate  cells  held 
together  by  a  mucilage- 
like secretion  of  the  cells. 

Each  cell  works  independently  in  getting  food,  breathing, 
giving  off  waste,  and  in  reproduction.  The  colony 
moves    by   lashing    the    water    with    long    protoplasmic 

55 


Figure  54.  —  Gonium. 


56 


THE  SIMPLER   METAZOA 


i 


/...'©" 


IMS? 


threads  (flagella),  two  of  which  project  from  each  cell. 
The  advantage  in  rate  of  movement  resulting  from  the 
union  of  cells  is  illustrated  in  rowing.  Eight  men  in 
a  large  rowing  shell  can  go  faster  than  one  man  in  a  single, 
small  shell.  In  reproduction,  the  sixteen  cells  fall  apart, 
and  each  one  grows  into  a  new  colony. 

40.  Volvox.  —  Volvox  is  a  colony  of  hundreds  of  tiny 
green  cells  embedded  in  a  hollow  gelatinous  sphere. 
Each  cell  has  two  flagella.     For  a  time  all  the  cells  are 

alike  and  share  equally  in  the 
work  of  the  colony.  But  in 
reproduction  only  a  few  cells 
take  part.  In  the  simplest 
method,  a  few  cells  grow  large 
and  escape  into  the  hollow 
sphere.  There,  they  divide 
and  grow  into  new  colonies. 
Finally,  the  mother  colony 
breaks,  and  the  daughter 
colonies  escape. 
The  more  complex  method  is  like  the  reproduction  of 
higher  animals.  Certain  cells  in  the  colony  grow  large 
and  escape  into  the  hollow  sphere.  They  are  the  egg 
cells.  Other  cells  of  the  colony  enlarge  and  divide  into 
large  numbers  of  slender,  free-swimming  cells  called  sperm 
cells.  The  sperm  cells  escape  into  the  hollow  sphere  and 
swim  about.  One  sperm  enters  an  egg  cell  and  unites 
with  it,  forming  a  single  cell,  the  fertilized  egg  cell,  which 
can  develop  a  new  colony. 

41.  Division  of  Labor.  — In  gonium,  the  cells  are  alike  in 
form  and  function,  but  in  volvox,  we  find  that  a  few  cells 
have  been  changed  in  form  in  order  better  to  perform  the 
special  work  of  reproduction.  This  is  the  first  step  in  the 
division  of  labor. 


& 


Figure  55.  —  Volvox. 


SPONGES  57 

This  is  well  shown  in  the  higher  animals,  where  certain 
cells  are  grouped  together  for  a  given  work.  The  diges- 
tive system  contains  cells  which  work  to  make  solutions  of 
the  food  eaten.  These  solutions  nourish  the  whole  body, 
not  the  cells  of  the  digestive  tract  alone.  Certain  other 
cells  are  modified  in  such  a  way  for  secreting  and  holding 
lime  that  they  form  bones  by  which  the  whole  body  is 
benefited. 

Some  cells  are  grouped  to  form  muscles  to  be  used  in 
securing  food  and  in  enabling  animals  to  escape  from 
their  enemies.  Other  cells  are  for  the  purpose  of  convey- 
ing and  interpreting  impressions,  so  that  the  animal  may 
hear  the  approach  of  an  enemy,  or  detect  the  presence  of 
food.  It  is  largely  the  carrying  out  of  this  "  division  of 
labor  "  that  tells  us  the  rank  of  an  animal  or  a  plant  in 
biological  classification. 

In  the  business  world  we  know  of  division  of  labor. 
Years  ago  the  cobbler  made  all  the  parts  of  a  shoe.  In 
our  large  shoe  factories  to-day  we  find  no  one  man 
making  an  entire  shoe.  One  man  runs  the  machine  that 
cuts  the  leather  and  does  no  other  part  of  the  work. 
He  may  have  been  a  cutter  twenty  years,  and  he  works 
rapidly  and  accurately.  Another  man  runs  the  machine 
which  sews  uppers  to  the  soles.  He,  too,  is  a  rapid  and 
skillful  worker.  Other  men  have  their  special  lines  of 
work  to  do.  In  the  end  they  produce  more  shoes  and 
better  shoes  than  this  same  number  of  men  could,  if  they 
were  all  cobblers  and  each  finished  his  product.  So  in 
the  world  of  business  we  find  the  same  plan  of  division  of 
labor  that  we  are  studying  in  biology. 

42.  Sponges. — Sponges  are  simple  metazoa.  In  them 
we  find  division  of  labor  carried  out  in  a  more  complex 
way  than  in  gonium  and  volvox.  Simple  sponges  have 
a  body  in  the  form  of  a  hollow  cylinder.      Water  enters 


58 


THE  SIMPLER   METAZOA 


through  the  sides  of  the  body  and  passes  out  through  a 
hole  in  the  top.  A  simple  sponge,  called  Grantia,  grows 
in  salt  water  attached  to  docks  or  other  objects  submerged 
along  the  seashore.  On  examination,  it  will  be  observed 
that  grantia  is  less  simple  than  volvox. 


Figure  56.  —  Bath  Sponge. 
A  skeleton. 

43.  Structure.  —  Grantia  is  composed  of  three  layers  of 
cells  which  show  division  of  labor.  The  inner  layer  is 
called  the  endoderm  (en'do-derm).  It  consists  of  cells 
provided  with  flagella  which,  by  their  movement,  produce 
a  current  of  water  through  the  central  cavity.  The 
water  enters  through  the  holes  in  the  sides  (inhalent 
pores)  and  is  forced  out  through  the  opening  at  the  top 
(exhalent  pore).  The  water  contains  food  particles 
which  the  cells  of  the  endoderm  have  the  power  to  take 
in  and  digest.  The  food  solution  is  passed  to  the  other 
cells   in   the    sponge    body    by    the    process   of   osmosis. 


STRUCTURE 


59 


&      it 


Figure  57.  —  Diagram. 
To  show  parts  of  sponge. 

This  is  a  physical   process  in  which  gases   or  liquids  of 
unequal  densities,  separated  by  a  plant  or  animal  mem- 
brane, tend  to  mix  and  become  alike,  the  liquids  or  gases 
passing  through  the  membrane. 
Thus    the    food    digested    is 
passed    on    and    nourishes    the 
cells  of   the   middle   and    outer 
layers.     The  cells  of  the  middle 
region   form   spicules   (spic'uls) 
of  lime   (Figure   58)  that   pro- 
ject   through   the   other   layers  Figure  58. 
and  strengthen  the  whole  body. 

The  outer  layer  or  ectoderm  (ek'to-derm)  serves  as  a 
protective  layer  and  with  the  help  of  the  spicules  gives 
definite  shape  to  the  body. 

LABORATORY   STUDY 

The  sponge  which  we  ordinarily  handle  is  simply  the  skeleton,  and  is 
easily  kept  from  year  to  year.  Examine  several  kinds  of  sponge  skele- 
tons and  compare  their  shape,  size,  and  the  nature  of  the  skeleton.     How 


60 


THE  SIMPLER   METAZOA 


much  water  will  the  pores  of  the  sponge  hold  ?  Microscopic  sections  of 
Grantia  are  necessary  if  you  are  to  make  out  the  inhalent  pores,  the 
central  cavity,  and  spicules. 

44.  Reproduction.  —  At  certain  times  of  the  year  the 
sponge  reproduces  by  means  of  two  kinds  of  cells  (eggs 
and  sperms)  developed  in  the  middle  layer.  A  sponge 
may  develop  both  eggs  and  sperms,  but  usually  develops 
only  one  kind  at  a  time.      Cells  from  the  middle  layer 

move  in  between  cells  of  the  endoderm 
and  grow  large  and  round.  These  are 
the  eggs  (female  cells).  Other  cells 
move  into  the  endoderm  layer  and  divide 
into  many  small  ciliated  cells  (the  sperm 
or  male  cells).  The  sperms  are  set  free 
and  escape  into  the  water  of  the  central 
cavity  and  out  from  the  body  of  the 
parent  sponge.  A  sperm  enters  the 
body  of  another  sponge  and  when  it 
finds  an  egg,  fuses  with  it,  thus  forming 
the  fertilized  egg.  The  fertilized  egg 
then  begins  to  grow,  and  after  a  definite 
period  breaks  away  from  the  parent, 
moves  about  for  a  time,  and  then  settles  down,  attaches 
itself,  and  grows  into  a  mature  sponge.  The  immature 
sponge  has  the  power  of  locomotion,  but  the  mature  form 
loses  this  power.     Nevertheless  the  sponge  is  an  animal. 

Reproduction  that  comes  about  through  the  fusion  of  an 
egg  and  a  sperm  is  called  sexual  reproduction.  The  other 
method  of  reproduction,  called  asexual  reproduction,  also 
occurs  among  sponges.  By  this  method,  sponges  form 
little  buds  or  branches  which  develop  into  new  sponges. 

45.  Spongilla.  — Spongilla  (spunj-il'la)  is  a  fresh-water 
sponge.  At  the  approach  of  cold  weather,  certain  repro- 
ductive bodies   are  formed,  known   as  winter-cells,    and 


Figure  59. — Two 
Stages  in  the 
Development  of 
the  Sponge. 


RELATION    TO   OTHER   ANIMALS  01 

these  escape  from  the  sponge.  They  settle  down  to 
the  bottom  of  the  pond  or  stream  and  remain  dormant 
until  the  approach  of  warm  weather,  when  they  grow  into 
new  sponges.  They  have  a  thick  protecting  coat  which 
enables  them  to  resist  unfavorable  conditions. 

46.  Economic  Importance.  — The  spicules  of  the  different 
sponges  form  a  large  part  of  their  so-called  skeletons. 
These  spicules  are,  in  some  cases,  composed  of  lime  and 
form  the  limy  sponges.  In  others,  they  are  of  silica  and 
form  the  glass}?"  sponges.  The  more  important  sponges 
have  a  skeleton  made  up  of  a  hornlike  substance  which  is 
flexible.     This  is  the  sponge  of  commerce. 

Great  quantities  of  sponges  are  gathered  from  the  sea 
by  divers  and  by  dredges.  The  living  tissues  arc 
allowed  to  decay,  and  the  skeletons  are  then  washed  and 
dried.  Some  are  bleached  to  form  the  white  sponges. 
The  sponges  of  best  quality  come  from  the  Mediterranean 
Sea  and  the  Red  Sea. 

Sometimes  fresh-water  sponges  grow  in  the  water  mains 
of  cities  and  towns,  causing  the  pipes  to  become  clogged. 

47.  Relation  to  Other  Animals.  — No  animal  is  known  to 
eat  the  sponge.  Sponges  themselves  feed  on  minute 
particles  of  food,  which  are  carried  in  by  the  currents  of 
water  produced  by  the  cilia  of  the  endoderm.  Some  marine 
animals  use  the  porous  body  of  the  sponge  as  a  retreat. 

Certain  sponges  live  in  close  relationship  to  higher 
forms  of  animals.  One  kind  is  always  found  growing  on 
the  legs  of  crabs.  The  movement  of  the  crab  carries  the 
sponge  to  water  richer  in  oxygen  and  food,  and  the  crab 
is  hidden  from  its  enemies  by  its  sponge  covering.  Each 
animal  gains  by  this  inter-relationship.  Where  two  such 
animals  as  the  crab  and  sponge  live  in  this  way  the  rela- 
tionship is  known  as  symbiosis  (sym-bi-o'sfe  :  Greek,  syn, 
with  ;   bios,  life). 


62  THE  SIMPLER   METAZOA 

SUMMARY 

The  transition  from  simple  Protozoa,  through  the  Colo- 
nial Protozoa,  to  the  Metazoa  is  simple  and  direct.  In 
gonium  and  volvox,  the  beginning  of  division  of  labor  is 
noticed  ;  that  is,  one  part  of  the  body  becomes  dependent 
on  another  part  for  certain  definite  things.  For  example, 
one  cell  is  devoted  to  securing  food,  while  another  produces 
eggs  or  sperms.  The  sponges  are  simple  Metazoa  in  which 
the  division  of  labor  has  taken  the  form  of  producing 
three  layers,  —  the  ectoderm,  or  outer  layer  ;  the  endo- 
derm,  or  inner  layer;  and  a  loosely  formed  middle  layer. 
Grantia  is  a  simple  sac-shaped  sponge  which  reproduces 
both  sexually  and  asexually.  The  general  manner  of 
development  by  the  sexual  process  is  essentially  the  same 
in  all  the  higher  animals,  including  man.  The  bath 
sponges  are  the  only  ones  of  economic  importance. 

QUESTIONS 

What  can  the  single-celled  protozoan  do  ?  Compare  with  the  Colonial 
Protozoa,  gonium  and  volvox.  Explain  the  meaning  of  division  of  labor 
in  an  animal.  In  what  respects  do  sponges  differ  ?  Of  what  use  are 
they  ?     Why  are  not  all  sponges  useful  ? 

REFERENCES 

Hegner,  Introduction  to  Zoology,  Chapter  VI. 
Jordan  and  Kellogg,  Animal  Life,  Chapter  II. 
Osborne,  Economic  Zoology,  Chapter  III. 


CHAPTER   V 


OCELENTERATES.     HYDRA-LIKE  ANIMALS 

48.  Ccelenterates. — -The     Coelenterates     (se-len'te-rats 
Greek,    koilos,    hollow  ;     enter  on,    intestine)    are    simple 
metazoa,  a  little  higher  in  development  than  the  sponges. 
In  the  group  are  hydras  (hl'dras),  hydroids  (hi'droids), 
jelly-fishes,  sea-anemone 

(a-nem'o-ne),    sea-fans, 
and  corals. 

49.  Structure  of  Hydra. 
—  The  hydra  is  an  in- 
teresting fresh  water 
animal  about  a  quarter 
of  an  inch  in  length. 
Its  body  is  shaped  like 
a  little  cylindrical  bag 
with  only  one  opening, 
the  mouth,  which  is 
surrounded  by  a  few, 
usually  six,  delicate, 
thread-like  arms  called 
tentacles  (ten'ta-kls). 
The  body  is  composed 
of  three  layers,  the 
outer  layer,  ectoderm ; 
the    middle    layer,    the 

mesoglea    (mes-o-gle'a  :         FlGURE  60.  -  m.crophotographs  of 
Greek,   mesos,    middle  ;  Hydra. 

G3 


64 


CCELENTERATES 


Figure  61.  —  Diagram  of  Body 
of  Hydra. 


gloios,  glutinous  substance)  ; 
and  the  inner  layer,  endo- 
derm. 

Each  layer  does  some  par- 
ticular work  for  which  the 
others  are  not  fitted.  For 
example,  the  outer  layer 
contains  cells  which  are 
especially  sensitive  to 
stimuli  and  many  modified 
muscle  cells  that  enable  the 
animal  to  move  about.  The 
inner  layer  contains  cells 
provided  with  flagella  which 
catch  the  food  particles  for 
the  inner  cells  to  digest. 
The  muscular  action  of  the 
outer  layer  moves  the  entire 
animal.  The  sensitive  cells  enable  the  animal  to  recog- 
nize its  prey.  The  food  digested  by  the  inner  layer  is 
used  by  all  the  cells  of  the  body.  Thus  we  see  an 
advance  in  the  division  of  labor  over  that  shown  in  the 
sponge.  We  shall  observe  a  still  greater  increase  in 
division  of  labor  as  we 
study  higher  animals. 

Tentacles  are  hollow, 
finger-like  branches  con- 
nected with  the  body 
cavity.  They  are  pro- 
vided with  stinging  cells 
which  help  the  hydra  to 
capture  living  water  fleas, 
and  the  like.  These 
stinging  cells  have  darts 


Figure  62. —  Microphotograph  of 
Body  Wall  of  Hydra. 


REPRODUCTION 


65 


which  are  automatically  discharged  when  the  tentacles 
come  in  contact  with  little  animals.  The  darts  stun  the 
prey  and  render  escape  impossible.  The  tentacles  sur- 
round the  food  and  carry  it  to  the  mouth,  which  opens 
directly  into  the  food  cavity.  The  action  of  the  tentacles 
in  doing  this  work  sug- 
gests the  idea  that  each 
tentacle  has  some  way 
of  realizing  the  efforts 


Endoderm 


Mesoglea 

Ectoderm 


Figure  63.  —  Diagram. 
To  explain  cell  layers  in  Figure  62. 


of  the  others. 

We  should  keep  in 
mind  that  in  the  meta- 
zoan  the  united  cells  are 
in  connection  with  each 
other  through    the   cell 

walls.  This  is  true  even  if  we  are  not  able  to  trace  the 
connections  with  the  microscope.  In  the  higher  animals 
we  shall  find  that  connections  between  cells  are  made  by 
means  of  nerve  cells.  The  development  of  a  nervous 
system  only  carries  out  division  of  labor  to  a  greater 
degree. 

50.  Respiration  and  Excretion.  —  By  osmosis,  oxygen  is 
absorbed  from  the  water  by  the  cells  of  the  ectoderm. 
The  water  that  enters  the  mouth  carries  oxygen,  and  by 
osmosis  it  is  absorbed  by  the  cells  of  the  endoderm.  At 
the  same  time  the  carbon  dioxide  from  the  cells  is  thrown 
off  into  the  water. 

51.  Reproduction.  —  The  hydra  reproduces  both  sexually 
and  asexually.  In  sexual  reproduction  eggs  and  sperms 
are  produced  by  the  ectoderm  cells.  The  sperm  cells 
escape  into  the  water  and,  like  sperm  cells  of  all  other 
animals,  have  the  power  of  locomotion.  The  fusion  of 
the  egg  cell  and  a  sperm  cell  starts  growth  which  results 
in   the  division    of   the  egg    cell    into    many  other  cells. 


66 


CCELENTERATES 


Hydras  also  reproduce  asexually  by  budding.  The  buds 
soon  separate  from  the  parent  and  begin  an  independent 
life.  Like  the  developing  sponge,  the  developing  hydra 
grows  until  it  finally  becomes  a  fully  formed  hydra. 


LABORATORY   STUDY 

The  living  brown  or  green  hydras  can  usually  be  found  in  the  spring  or 
fall  in  most  fresh  water  ponds.  They  are  easily  collected  by  gathering 
the  floating  leaves  and  overhanging  grass  that  is  immersed  in  the  water. 
Place  this  collection  in  a  glass  jar  in  the  laboratory.  In  a  couple  of  days 
the  hydras  will  have  moved  from  the  grass  to  the  sides  of  the  jar.  They 
can  be  examined  by  a  small  magnifying  glass  in  the  jar  or  be  transferred 
to  a  watch  glass  and  observed  under  the  low  power  of  the  microscope. 
Watch  the  hydra  contract,  when  jarred  or  touched.  Note  that  the  tentacles 
become  very  short.  Try  feeding  with  a  small  bit  of  raw  meat.  Make 
out  the  transparent  ectoderm  and  the  darker  endoderm.  Are  there  any 
buds  ?     What  happens  to  the  buds  when  the  parents  contract  ? 

52.  Hydroids.  — Hydroids  are  marine,  hydra-like  animals 
which  are  united  in  groups  forming  a  tree-like  colony 
(Figures   64-66).      They  are  often  mistaken  for  plants. 


Figure  64. —  Microphotograph 

OF    THE    HYDROID    ObELIA. 


Figure  65.  —  Diagram  of  the 
Hydroid  Bougainvillea. 


HYDROIDS 


67 


When  the  young  hydroid  first  begins  to  grow,  it  looks 

like  the  fresh  water  hydra  (Figure  60). 

As  the  hydroid  grows,  branches 
form  and  on  the  end  of  each  branch, 
tentacles    and     a    mouth     appear. 


Figure  66. —  A  Hy- 
droid Colony  that 
Looks  like  a 
Plant. 


Figure  67.  —  A  Hydroid  Medusa. 


Each  branch  is  able  to  capture  food  and,  after  it  takes 
what  it  needs,  the  surplus  is  distributed  to  other  parts. 
This  is  easily  brought 
about,  as  a  common 
digestive  cavity  con- 
nects all  of  the  branches. 
The  hydroid  is  termed 
a  colony  because  all  of 
the  branches  are  united 
and  help  each  other  in 
getting  enough  food  for 
all. 

Some  of  the  hydroids 
form  curious  buds  which 
develop  into  medusce 
(me-du'se).    See  Figure 

^  °  Figure  68.  —  The  Medusa  Known  as 

bi.      As    soon    as    the  Pelagia 


68 


CCELENTERATES 


medusae  are  set  free  from  the 
hydroids,  they  swim  about  and 
capture  their  own  food.  Each 
medusa  is  provided  with  either 
ovaries  (o'va-riz),  organs  which 
grow  egg  cells,  or  spermaries 
(speYma-riz),  organs  which 
grow  sperm  cells.  When  the 
eggs  and  sperms  mature,  they 
are  discharged  into  the  water. 
A  single  sperm  cell  must  fuse 
with  an  egg  cell  before  the 
egg  can  begin  to  grow.  This 
union  of  these  two  cells  is 
called  fertilization.  The  egg 
grows  into  an  embryo  (em'- 
bri-o),  an  immature  stage  dif- 
fering in  different  animals, 
and  this  gradually  changes  into 
a  small  hydroid.  The  several 
steps  in  this  complicated  series 
of  changes  are  illustrated  in 
Figure  69.  The  hydroids 
and  medusa3  show  a  form  of 
reproduction  called  alternation 
of  generations,  that  is,  they 
reproduce  alternately  sexually 
and  then  asexually. 

53.  Sea-anemone. — Sea-anemo- 
nes are  animals  allied  to  the 
hydra.       The   interior   of   the 


J  <^k 

Figure  69.  —  Pennaria  Tiarella. 

a.  The  hydroid  colony  ;  b,  one 
of  the  female  medusae,  much 
enlarged ;  c,  the  egg  of  the 
medusas  beginning  to  segment 
after  it  has  been  fertilized; 
d,  e,  f,  further  segmentation 
stages ;  g,  the  blastula  stage ; 
h,  the  free  swimming  larva 
(planula)  ;  i\  /,  and  k  show  the 
gradual  transformation  of  the 
larva  into  a  hydra-like  colony. 
Branches    grow    on    the    stage 

shown  in  k  until  a  colony  like  a  results.  This  is  the  form  that  alterna- 
tion of  generations  takes  in  this  hydroid.  (Arranged  from  a  monograph 
on  Pennaria  by  C.  W.  Hargitt.) 


CORAL 


69 


body  cavity  is  subdivided  by  many  partitions  which  in- 
crease the  digesting  and  absorbing  surface.  The  sea- 
anemone  reproduces  by  eggs  and  sperms. 

The  resulting  embryo  is  free  at  first,  but  later  becomes 
fixed  to  some  object  and  develops  into  the  sea-anemone. 
There  is  no  medusa  stage. 

54.  Coral.  —  Geographies  tell  us  of  the  many  coral  islands 
and  reefs  built  up  by  the  coral  animals.  These  animals 
are  coelenterates,  most 
of  them  closely  allied 
to  the  sea-anemone, 
but  the  coral  animal 
secretes  about  the  body 
and  along  the  parti- 
tions calcareous  (kal- 
ka/ re-us,  limy)  skele- 
tons which  form  the 
stone-like  masses  of  the 
coral  rock.  The  upper 
portion  of  the  coral 
rocks  is  alive  with 
these  coral  animals. 
The  lower  portion  is  made  up  of  skeletons  only.  Suc- 
ceeding generations  build  upon  the  work  of  their  ancestors. 

Corals  reproduce  much  as  trees  grow  branches,  but  at 
certain  periods  eggs  and  sperms  are  produced  as  in  the 
sea-anemone.  Then  the  embryo  settles  down,  secretes  its 
own  skeleton,  and  this  is  added  to  the  work  of  other 
corals. 

Sea-fans  and  sea-plumes  are  coelenterates  which  have  the 
forms  suggested  by  their  names.  A  dried  specimen  of 
either  looks  as  if  a  branch  had  been  dipped  in  a  solution 
and  coated.  The  interior  is  of  a  horny  substance.  The 
exterior  is  covered  with  a  limy  secretion. 


Figure  70.  —  Some  Common  Corals. 


70  CCELEN  TERA  TES 

55.  Economic  Importance.  —  The  corals  alone  of  the 
coelente rates  are  of  economic  importance ;  they  add  to 
many  islands,  protect  others  from  being  washed  away,  and 
in  some  cases  form  entirely  new  islands. 

SUMMARY 

The  hydra-like  animals  represent  an  advance  in  the 
division  of  labor.  The  layers  of  their  bodies  are  more 
definite  and  do  their  work  better  than  in  the  sponges. 
Hydroids  and  the  corals  illustrate  the  formation  of  a 
colony.  In  some  of  the  colonies  the  division  of  labor  is 
more  extensive  than  in  others.  The  economic  importance 
of  the  corals  has  been,  and  continues  to  be,  very  great. 

QUESTIONS 

Explain  fully  how  the  hydra  gets  its  food  and  how  some  of  this  food 
finally  nourishes  the  ectoderm  cells.  Compare  the  hydra  and  the  hydroid. 
In  what  are  they  alike  ?  In  what  are  they  different  ?  How  does  the 
hydra  reproduce  ?  How  does  the  hydra  get  its  oxygen  ?  Explain  how 
the  coral  animal  has  been  able  to  form  islands. 

REFERENCES 

Darwin,  Structure  and  Distribution  of  Coral  Reefs. 
Hegner,  Introduction  to  Zoology,  Chapter  VIII. 


CHAPTER   VI 


THE  STARFISH  FAMILY.     (Optional) 

56.  The  Starfish  Group.  —  This  group  of  animals  includes 
the  well-known  starfish,  the  sea-urchins,  sea-lilies,  and 
several  soft-bodied  forms  such  as  the  sea-cucumber.  The 
technical  name  for  these  different  animals  is  echinoderm 
(e-km'6-derm  :  Greek,  echinus,  spine  ;  derm,  skin),  mean- 
ing spiny-skinned  animals.  Most  of  these  animals  have  a 
skeleton.     Unlike  that  of 

man  it  is  on  the  outside 
and  is  composed  of  cal- 
careous plates.  In  some 
forms,  like  the  starfish, 
the  plates  are  embedded 
in  the  skin,  while  in  the 
sea  urchin  the  plates  fit 
edge  to  edge,  forming  a 
shell.  The  plates  support 
many  spines  which  project 
out  over  the  body  giving 
the  spiny  appearance  char- 
acteristic   of    the    group. 

Both  the  skeleton  and  soft  parts  are  arranged  in  a  radial 
manner.  The  presence  of  spines  and  the  radial  arrange- 
ment are  two  characters  by  means  of  which  one  can 
recognize  most  of  the  echinoderms. 

57.  The  Starfish. — Starfishes  are  found  in  salt  water. 
They  are  composed  of  a  central  region,  called  a  disk,  from 

71 


Figure  71.  —  Starfish. 


72 


THE  STARFISH   FAMILY 


which  extend  five  arms  or  rays.  On  the  disk  is  a  porous 
circular  plate.  It  is  known  as  the  madreporic  plate 
(mad-re-por'ik  :    Greek,  mater,  mother  ;   poros,  soft).      It 


3 


Tfu1 


Figure  72.  —  Diagram  of  Body  of  Starfish. 

c,  liver ;    v,  stomach  ;    o    mouth  ;   g ,  reproductive  glands  ;   p,  tube 

feet ;    s,  stone  canal. 

serves  to  take  water  into  a  series  of  vessels  by  means  of 
which  the  animal  moves  and  holds  on  to  rocks  and  shells 
at  the  sea  bottom 

58.  Internal  Structure.  —  If  the  upper  portion  of  the 
animal  is  removed  carefully,  the  internal  structure  can 
be  examined.     Each  ray  is  nearly  filled  with  masses  of 

yellowish  green  sub- 
stance. This  is  a  gland 
which  forms  the  diges- 
tive fluids  used  in  the 
stomach.  The  wrinkled 
mass  in  the  region  be- 
neath the  disk  is  the 
stomach.  The  mouth  is 
just  below  the  stomach 
on  the  lower  or  oral  side 
of  the  body.  At  the 
angles  of  the  arms  and 
extending  into  each  ray 
are      the      reproductive 


Pi 


Figure  73.  — Anatomy  of  the  Starfish,     glands,    which    vary    in 


LOCOMOTION  73 

size  at  different  ages  and  seasons.  According  to  the  sex 
of  the  individual  these  glands  produce  either  eggs  or 
sperms,  which  are  discharged  into  the  water. 

LABORATORY   STUDY 

Dried  specimens  of  starfish  serve  well  for  general  study.  These  may 
be  compared  with  specimens  which  have  been  preserved  in  alcohol  or 
formalin.  Work  out  the  several  parts  such  as  disk,  arms,  madreporic 
plate,  spines,  groove  of  the  feet,  and  position  and  form  of  the  mouth.  If 
skeletons  of  sea  urchins  are  available,  they  are  interesting  for  comparison. 

59.  Life  History.  —  The  eggs  and  sperms  fuse  outside 
the  body.  In  their  development  into  adults  they  pass 
through  a  series  of  striking  changes.  The  young  or 
larval  forms  do  not  resemble  the  adults  at  all.  This  de- 
velopment through  a  series  of  marked  changes  is  as 
striking  as  that  seen  in  the  insects  and  is  likewise  called 
a  metamorphosis. 

60.  Food  Taking.  —  The  starfish  takes  its  food  in  an  un- 
usual manner.  Most  animals  move  the  food  to  the  mouth, 
swallow  it  or  engulf  it,  and  digest  it  within  the  body 
cavity.  In  the  case  of  the  starfish  we  find  that  the 
stomach  is  projected  through  the  mouth  and  made  to 
surround  its  food.  In  this  position  it  digests  and  assimi- 
lates the  food  and  then  withdraws  its  stomach  through 
the  mouth  and  moves  on  slowly  to  some  other  place.  A 
common  food  of  the  starfish  is  the  clam.  The  arms  or 
rays  surround  the  clam,  and  the  "hinge  ligament"  which 
holds  the  shell  together  is  tired  out,  thus  causing  the 
protecting  clam-shells  to  separate.  The  stomach  is  then 
pushed  out,  enveloping  the  clam.  The  digestive  fluid  is 
secreted  and  the  dissolved  clam  is  absorbed  as  food. 

61.  Locomotion,  —  The  animal  moves  chiefly  by  means  of 
the  tube-like  feet  found  in  the  groove  on  the  under  surface 
of  the  rays.     These  so-called  feet  make  little  sucking  disks. 


74 


THE   STARFISH   FAMILY 


Figure  74. —  Purple  Sea  Urchin. 


62.  Respiration. — Oxy. 
gen  is  taken  from  the 
water  and  carbon  dioxide 
given  off  through  little 
thin-walled,  gill-like 
processes  which  cover 
the  upper  surface  of  the 
disk  and  arms.  These 
gill-like  processes  pro- 
ject through  holes  in 
the  exoskeleton. 

63=  Other  Echinoderms. 
—  The  sea  urchins  are 

thickly  covered  with  spines  and  have  tube  feet  which,  in 

many  cases,  may  be  greatly  extended.    When  the  spines  are 

removed,  an  exoskeleton  is  revealed,  which  readily  shows  the 

radial  arrangement  characteristic  of  the  echinoderm  group. 
64.   Economic  Importance  of  the  Group.  —  Of  echinoderms 

the   starfish   alone   has    an    eco- 
nomic bearing.     It   is  harmful. 

Living  as  it  does  in  the  region 

of    the    oyster    and    clam    beds 

and   feeding  almost  exclusively 

on  them,  the   starfish    annually 

destroys    thousands    of    dollars' 

worth    of    clams     and    oysters. 

By  removing  the  seaweed  where 

the  immature  starfish  gather  and 

by  dragging  the  oyster  and  clam 

beds  great  numbers  of  starfish 

are  destroyedc 

In  former  times  the  fishermen 

used  to  break  starfish  to  pieces 

on  the  side  of  the  boat  and  throw  Figure  75.  —  Sea  Lily. 


ECONOMIC  IMPORTANCE  75 

them  back  into  the  water.  It  is  now  known  that  by  bo 
doing  they  were  but  increasing  the  number  of  starfish,  for 
starfish  have  the  power  to  re-grow  the  parts  broken  orf\ 
Each  complete  arm  could  reproduce  an  entire  starfish. 
This  power  to  restore  lost  parts  is  known  as  regeneration 
(re-jen-er-a'shun).  Many  of  the  lower  animals  have  this 
power  to  a  marked  degree,  and  all  animals  have  it  to 
some  degree. 

SUMMARY 

The  starfish  group  of  animals  is  known  by  the  presence 
of  spines  in  the  skin  and  a  radial  arrangement  of  the 
organs.  Their  chief  economic  relation  to  man  consists  in 
their  great  destructiveness  to  the  oyster  and  clam  beds. 

QUESTIONS 

Why  are  starfish  so-called?  How  can  they  be  distinguished  from 
other  animals  ?  How  do  they  move  ?  Where  do  they  live  ?  On  what 
do  they  feed  ?     How  do  they  breathe  ? 

REFERENCES 

Brooks,  The  Oyster. 

Osborne,  Economic  Zoology,  Chapter  VIII. 

Poulton,  All  About  the  Oyster. 


V 


CHAPTER   VII 

THE  WORM  GROUP 

65.  The  Worm  Group.  —  Here  are  found  several  distinct 
groups  of  animals  that  in  advanced  text-books  of  zoology 
are  treated  separately.  The  word  "worm  "  is  an  old  term 
which  properly  describes  such  animals  as  the  earthworm, 
sea  worm,  leech,  tapeworm,  flat  worm,  and  a  few  others. 
The  word  "  worm '  cannot  be  correctly  used  for  such 
larvae  of  insects  as  the  "  apple  tree  worm  "  or  "  currant 
worm." 

The  worm  group  is  divided  into  two  classes  —  those 
whose  body  is  composed  of  numerous  segments  (seg'ments) 
or  rings,  such  as  the  earthworm,  the  sea  worm,  and  the 
leech ;  and  those  whose  body  is  not  segmented,  such  as 
the  tapeworm  and  flat  worm.  The  first  class  comprises 
the  true  worms,  which  are  known  as  Annelida  (a-nel'I-da). 
The  second  class,  the  unsegmented  worms,  have  no  single 
technical  name,  and  are  not  believed  by  scientists  to  be 
true  worms.  They  comprise  a  number  of  worm-like  ani- 
mals which  have  hardly  any  features  in  common.  Here 
are  found  the  fresh  water  planarians,  the  parasitic  tape- 
worms, liver  flukes,  and  numerous  round  worms,  of  which 
the  hair  worm  is  an  example. 

The  planarian  worm  is  one  of  the  simplest  of  these  un- 
segmented worms.  It  is  found  under  stones  submerged 
in  stagnant  water  and  in  streams.  It  is  frequently 
brought  into  the  laboratory  and  lives  easily  in  aquaria. 

76 


®: 

H 

Mi 

t* 

&2» 

Figure 

76.- 

-A 

Pla 

narian  Worm. 

TRICHINA  77 

The  liver  fluke  is  a  parasitic  flat  worm  which  each  year 
causes  the  death  of  many  sheep  by  injuring  their  livers.1 
Like  some  other  parasitic  animals  the  liver  fluke  requires 
two  hosts  to  complete  its  development.  The  hosts  of  the 
fluke  are  the  sheep  and  certain  snails.  The  adult  liver 
flukes  form  eggs  and  sperms  in  the  liver  of  the  sheep. 
The  fertilized  eggs  par- 
tially develop  in  the 
sheep  ;  then  as  embryos 
they  pass  down  the  bile 
duct  into  the  intestine 
and  then  out  of  the 
body. 

The  ciliated  (sil'i-a-ted)  larva  then  makes  its  way  into 
water  or  along  dew-covered  grass.  If  it  comes  in  contact 
with  a  water  snail  in  the  water  or  a  land  snail  on  the  grass, 
it  enters  the  body  of  its  second  host,  otherwise  it  dies. 
Once  inside  the  body  of  the  snail  it  completes  a  compli- 
cated development.  By  a  bud-like  process  many  young 
flukes  are  formed  which  finally  emerge  from  the  snail  and 
make  their  way  to  the  grass  stems  on  which  they  encyst 
themselves.  If  this  grass  is  eaten  by  a  sheep,  the  diges- 
tive fluids  set  free  the  young  fluke  which  goes  up  the  bile 
ducts  to  the  liver,  where  it  grows  to  maturity. 

66.  Trichina.  —  Another  unsegmented  worm  that  is  of 
economic  importance  is  the  Trichina  (tri-klma),  now  gen- 
erally called  Trichinella  (tri'ki-neTla).  This  worm  lives 
in  the  intestine  of  mammals  and  from  the  intestine  mi- 
grates into  the  muscles  of  its  host.  In  the  muscle  it 
becomes  encysted  and  remains  until  the  flesh  is  eaten  by 
some  other  mammal.  When  pork,  infected  with  this 
parasite  and   insufficiently  cooked,   is  eaten  by   man  the 

1  The   Animal  Parasites  of  Sheep.     Dr.  Cooper  Curtice.     Bureau    Animal 
Industry,  United  States  Department  of  Agriculture,  1890. 


78 


THE   WORM  GROUP 


m 

■  ■■ 


esMIh  M?^  va  a ■■■■ 

'•'   .  1§  v  i\*f    '^^f  if) , 


Figure  77. — Trichi- 

NELLA. 


cysts    are    dissolved    by   the    digestive 
fluids  and  the  worms  are  freed. 

These  worms  then  develop  eggs  and 
sperms  which  after  uniting  mature  into 
young  worms  and  migrate  through  the 
intestine  into  the  muscles.  The  activity 
of  the  worms  at  this  stage  causes  a  seri- 
ous inflammation  of  the  tissues  and  a 
disease  known  as  trichinosis  (trik-in- 
o'sis),  which  is  often  fatal.  Hogs  con- 
tract trichinosis  by  eating  refuse  that 
contains  the  encysted  worms. 

Government  inspectors  examine  pork 
which  is  to  be  exported  or  sold  in  large 

quantities  to  see  that  it  is  free  from  these  parasites.     The 

smaller  sales  of  pork  by  local  dealers  are  not  inspected 

and  the  only  way  to  be  sure  of  the  harmlessness  of  the 

meat  is  to  cook  it  thoroughly. 

Hair  Worm.  —  The  only  importance  that  can  be  attached 

to  these  worms  is  the  myth  about  their  origin.      In  almost 

every  school  will  be  found 

students    who    believe    that 

horse  hairs  placed  in  water 

will     develop     into     "  hair 

snakes."       It    would    be    a 

pity   if   a  student  still   be- 
lieved this  after  a  course  in 

biology. 

Let   us    see    how   such   a 

belief     can     originate     and 

often     be     thought     to     be 

proved.      The    hair   snakes 

live    for    a    time    in    water 

and    often    in    the    watering      Figure  78.  — A  Common  Tapeworm. 


HAIR   WORM  79 

troughs  where  horse  hairs  are  also  found.  Boys,  and 
men  too,  sometimes  put  horse  hairs  in  water  and  then 
after  a  few  weeks  examine  the  water  and  find  these  hair 
snakes.  They  conclude,  since  they  put  in  the  hairs 
and  later  found  the  "hair  snakes,"  that  the  hairs  grew 
to  form  the  snakes  or  small  round  worms.  If  they  had 
been  as  careful  to  look  before  any  hairs  were  put  iu,  they 
would  have  seen  these  "hair  snakes ':  swimming  about. 
A   better  test   is   to   take  a  bottle  of  water,  put  in  the 


Figure  79.  —  Hair  Worm  in  Body  of  Grasshopper. 

hairs,  and  watch  for  developments.  Such  a  test  would 
show  that  no  hairs  turn  into  hair  snakes. 

Hair  snakes  have  a  complete  life  history  as  clearly  de- 
fined as  other  worms.  They  lay  eggs  which  fuse  witli 
sperms  and  form  larvae.  These  larvse  live  as  parasites  in 
the  bodies  of  insects  and  fishes  and  when  mature  make 
their  way  out  of  the  bodies  of  their  hosts.  It  would  be 
natural,  then,  to  find  them  in  pools  where  horses  drink 
and  these  parasitized  fishes  live,  or  in  watering  troughs 
into  which  grasshoppers  may  have  jumped,  as  they  so 
often  do. 

We  know  at  present  no  way  in  which  lifeless  matter 
can  be  made  to  live.  A  hair  cannot  become  a  worm  and  a 
crooked  stick  cannot  grow  into  a  snake.  New  life  comes 
from  the  old.     We  sometimes    read  in    the    papers    that 


80  THE   WORM  GROUP 

some  one  has  produced  life  from  chemicals,  but  it  is  not 
believed  at  the  present  time  to  be  possible. 

67.  The  Earthworm  is  the  simplest  and  best  animal  to 
illustrate  the  annelid  group  of  true  worms. 

When  one  examines  a  living  earthworm,  the  head  end 
can  be  determined  as  the  one  which  first  moves  forward. 
Actually  there  is  no  head  nor  are  there  special  sense 
organs.  The  muscles  in  the  front  end  are  stronger  and 
the  body  rounder  than  in  the  back  end.  The  back,  or 
dorsal  (dor's'l)  part,  of  the  worm  is  exposed  to  the  light 
and  is  darker  in  color  than  the  rest.  This  surface  is 
rounder  than  the  opposite  (under)  one  which  is  in  con- 
stant touch  with  the  dirt  when  the  worm  is  crawling. 
The  flat  surface  upon  which  the  worm  crawls  is  the  ven- 
tral (ven'tral)  surface. 

The  body  of  the  earthworm  is  made  up  of  a  number  of 
segments  (rings)  which  are  marked  off  by  shallow  grooves. 
Some  of  the  segments  in  the  front  end  are  larger  than 
those  that  make  up  the  back  end,  but  all  are  similar  in 
shape.  The  number  of  segments  depends  mostly  upon 
the  age  of  the  earthworm,  and  is  from  60  to  150  in  full- 
grown  worms. 

68.  Locomotion.  —  The  earthworm  crawls  by  means  of 
short,  stiff  bristles  used  as  legs,  the  seta?  (se'te  :  Latin, 
seta,  bristle),  which  are  found  in  all  of  the  segments 
except  the  first  two  or  three.  These  setce  are  arranged 
in  four  rows,  two  in  each  row.  To  understand  how  the 
setse  are  used  in  the  locomotion  of  the  earthworm  it  is 
necessary  to  know  that  the  body  wall  contains  two  mus- 
cular layers.  In  the  outer  layer  the  muscles  running 
around  the  body  are  called  circular  muscles.  The  inner 
layer,  consisting  of  a  number  of  bands  running  in  the 
direction  of  the  length  of  the  body,  are  called  longitudi- 
nal muscles.      The   contraction   of    the    circular   muscles 


INTERNAL  STRUCTURE  81 

lengthens  the  body  and  the  contraction  of  the  longitudinal 
muscles  shortens  it.  The  seta3  are  connected  with  the 
longitudinal  muscles.  By  pointing  the  set;e  backward 
and  bracing  them  against  the  ground,  the  worm  can 
push  itself  forward.  By  pointing  the  setae  forward  tin- 
worm  can  instantly  change  the  direction  of  its  movement. 

LABORATORY   STUDY 

One  of  the  annelids  should  be  studied  with  some  care,  as  an  illustration 
of  an  invertebrate  animal.  How  do  you  determine  the  anterior  and 
posterior  ends  ?  Dorsal  and  ventral  surfaces  ?  The  number  of  segments  '.' 
Compare  several  worms.  The  back  region  of  the  worm  shows  the  most 
variation  because  new  segments  are  being  added.  Where  are  the  setae  ? 
How  does  the  earthworm  move  ?  Place  it  on  a  glass.  The  front  region 
of  the  body  is  most  sensitive  to  touch.     Test  it. 

69.  Internal  Structure  of  Earthworms.  —  This  is  shown 
diagrammatically  in  Figure  80.  The  internal  structure 
consists  of  an  outer  tube, 
the  body  wall,  and  an 
inner  tube,  the  digestive 
tube.  The  space  be- 
tween the  body  wall  and 


f"iji  yr 


tdui         wen 


digestive  tube  is  known  FlGURE  8o.- Diagram. 

as    the     body    cavity    or      The  organs  of  earthworm  from  the  side. 

coelome  (se'liim  :   Greek, 

koilos,  hollow).     Thin  sheets  of  membrane  pass  from  each 

furrow  between  the  segments  to  the  digestive  tube. 

Beginning  at  the  front  end  the  digestive  tube  is  given 
certain  names  for  each  distinct  region,  as  follows  :  the 
mouth  cavity;  the  pharynx  (far'inks),  with  its  thick 
muscular  walls  ;  the  esophagus  (e-sof'a-giis),  thin- walled 
and  small  ;  the  crop,  a  wide  pouch  ;  the  gizzard,  where 
food  is  ground;  and  the  stomach-intestine,  a  large,  thin- 
walled  tract  extending  through  the  last  twro  thirds  of  the 
length  of  the  worm. 


82 


THE   WORM   GROUP 


The  earthworm  has  an  easily  recognized  nervous  system 
which  is  found  beneath  the  digestive  tube.  It  consists  of  a 
continuous,  minute,  white  thread  with  slight  swellings  in 
each  segment.  From  these  swellings,  which  are  called 
ganglia  (gan'gli-a:  Greek,  ganglion,  swelling  or  tumor), 
short   branches  extend   to  the  digestive  tube  and    other 

organs.  These  branches  are  known  as 
nerves.  Toward  the  front  end  the 
nerve-thread  parts  and  becomes  double. 
Each  part  passes  around  the  front  end 
of  the  pharynx  and  enlarges  to  form 
two  ganglia,  the  largest  found  in  the 
earthworm.  More  nerves  grow  from 
these  two  large  ganglia  than  from  any 
of  the  others  and  so  the  term  "  brain ' 
is  given  to  these  two  ganglia  found  in 
the  dorsal  surface  of  the  pharynx 
(Figure  81). 
The  organs  of  the  earthworm  are  supplied  with  blood 
which  is  carried  in  a  large  dorsal  blood  vessel,  a  ventral 
blood  vessel,  and  numerous  branches.  The  blood  is 
pumped  by  the  contracting  of  the  dorsal  vessel  and  by  the 
five  pairs  of  tubes  which  pass  from  the  dorsal  to  the 
ventral  vessel  around  the  esophagus.  These  five  tubes 
are  named  aortic  (a-6r'tlk)  arches. 


Figure  81. —  Earth- 
worm. 

Front  end  of  nervous 
system. 


LABORATORY   STUDY   OF  INTERNAL   STRUCTURE 

Work  out  the  internal  structure  of  the  earthworm.  In  dissecting,  cut 
the  skin  along  the  dorsal  surface,  being  careful  to  cut  the  many 
membranes  that  hold  the  digestive  tube  in  place.  Work  out  the  size  and 
position  of  the  mouth  cavity,  pharynx,  esophagus,  crop,  gizzard,  and 
stomach-intestine.  The  white  reproductive  organs  are  located  beside  the 
esophagus.  Locate  the  "brain,"  the  ventral  chain  of  ganglia.  The 
dorsal  blood  vessels  and  aortic  arches  should  be  located.  Make  a  sketch 
locating  the  organs  in  their  respective  segments. 


EXCRETION  83 

70.  Life  History.  —  In  the  starfish  group  the  sexes  are 
distinct.  The  sexes  in  the  annelids  are  distinct  in  some 
forms  and  in  others  the  same  individuals  have  both 
ovaries  and  spermaries.  However,  the  sperms  that  unite 
with  eggs  always  come  from  another  worm.  During  the 
season  when  the  ovaries  and  spermaries  are  forming  eggs 
and  sperms,  certain  segments,  usually  six  in  number,  be- 
ginning with  the  twenty-eighth  segment,  and  known  as 
the  clitellum  (kli-tel'liim),  pour  out  a  gelatinous  secretion 
which  hardens  into  a  collar-like  sac  around  the  worm. 

This  sac  is  worked  forward  and  as  it  passes  the  openings 
of  the  reproductive  organs,  eggs  and  the  sperms  from 
another  worm  are  pushed  into  it.  The  sac  continues  to 
move  forward  and  finally  leaves  the  worm  as  a  closed 
capsule.  This  capsule  contains  eggs,  sperms,  and  fluid 
food.  After  the  fusion  of  the  eggs  and  sperms,  the  re- 
suiting  embryonic  worms  begin  to  feed  upon  the  fluid 
food  in  the  capsule;  later  they  feed  upon  each  other 
until  but  one  may  remain  eventually  to  bore  or  eat 
its  way  to  the  earth  outside.  From  now  on  the  food  of 
the  young  worm  is  the  soil. 

The  earthworm  is  an  example  of  an  animal  which  has 
both  ovaries  and  spermaries. 

71.  Respiration.  —  Oxygen  passes  through  the  skin  di- 
rectly into  the  blood,  which  then  carries  the  oxygen  to  the 
various  cells  of  the  body.  The  outer  surface  must  be 
kept  moist  to  permit  the  skin  to  act  as  a  lung. 

72.  Excretion.  —  In  each  segment  is  found  a  pair  of 
organs  known  as  nephridia  (ne-fiid'i-a),  which  look  like 
little  threads.  These  remove  the  liquid  waste  and  carry 
it  to  the  outside  of  the  body.  It  is  believed  that  carbon 
dioxide  passes  off  through  the  skin,  much  as  oxygen 
passes  in.  This  taking  in  and  giving  off  of  these  gases 
is  accomplished  by  osmosis. 


84 


THE  WORM  GROUP 


73.  Food-taking.  —  The  food  of  the  earthworm  is  chiefly 
the  soil  in  which  it  burrows.  By  means  of  an  upper  lip, 
which  is  a  specialized  anterior  segment,  and  the  muscular 
walls  of  the  pharynx,  it  takes  the  earth  into  its  body  and 
the  muscles  of  the  digestive  tube  advance  the  food  along 
its  course.  The  soluble  and  therefore  digestible  parts 
are    absorbed,   and   the   remainder   (the  greater  portion) 

is  passed  along  to  the  outside.  Earth- 
worms are  not  critical  in  the  selection  of 
their  food,  although  they  are  not  entirely 
without  a  sense  of  taste. 

74.  Economic  Importance.  —  The  value 
of  the  earthworms  to  agriculture  is  too 
great  to  be  overestimated.  In  burrow- 
ing their  way  through  the  soil  they  leave 
passageways  for  water  and  air  to  enter, 
thus  assisting  plants  to  grow.  They 
bring  the  fertile,  swallowed  soil  to  the 
surface.  When  the  large  numbers  of 
the  earthworms  are  considered,  it  is 
obvious  that  they  are  the  great  natural 
cultivators  of  the  soil. 
75  Other  Annelids.  — The  sand  worm  or  Nereis  (ne're-is), 
a  marine  or  salt  water  form,  is  another  segmented  annelid. 
It  is  more  highly  specialized  than  the  earthworm,  for  it  has 
biting  mouth  parts,  tentacles,  and  eyes.  It  is  an  active 
swimmer  at  times.  The  development  of  the  sand  worm 
exhibits  metamorphosis,  while  the  earthworm  hatches  di- 
rectly into  a  worm  without  metamorphosis. 


Figure  82.  —  Dero. 

A  common  fresh- 
water annelid. 


SUMMARY 


In  the  worm  group  are  included  the  unsegmented  worms, 
such  as  tapeworms,  liver  flukes,  and  hair  worms ;  and  the 
segmented    or   true  worms  such  as   the  earthworms,  sea 


SUMMARY  s;> 

worms,  and  leeches.  All  of  these  worms  have  more  per- 
fectly organized  parts  than  the  sponges  and  hydroids. 
The  body  of  the  earthworm  shows  the  first  steps  in  tin- 
formation  of  definite  front,  back,  and  ventral  regions.  The 
digestive  tube  is  also  specialized  into  pharynx,  esophagus, 
crop,  gizzard,  and  stomach-intestine  ;  and  the  name  brain 
may  be  given  to  a  slightly  enlarged  portion  of  the  anterior 
end  of  the  nerve  cord.  Small  worms  of  various  kinds  are 
numerous  in  stagnant  water.  Some  live  as  parasites  in 
man  and  other  animals,  causing  much  suffering  and  loss 
of  life.  The  earthworm  as  a  cultivator  of  the  soil  has  been 
of  inestimable  value  to  man. 

QUESTIONS 

"What  kind  of  animals  are  called  worms  ?  Is  it  proper  to  call  "  cur- 
rant worms"  worms  ?  Why  not  ?  What  are  they  ?  How  do  you  recog- 
nize the  anterior,  posterior,  dorsal,  and  ventral  regions  ?  Compare  the 
grasshopper  or  some  other  insect  with  the  worm.  Explain  how  the  earth- 
worm moves ;  makes  its  burrow.  Compare  the  digestive  tube  with  the 
digestive  sac  of  the  hydra. 

REFERENCES 

Darwin,  Earthworms  and  Vegetable  Mould. 

Jordan,  Kellogg,  and  Heath,  Animal  Studies,  Chapter  VI. 

Sedgwick  and  Wilson,  General  Biology. 


CHAPTER   VIII 


CRUSTACEANS  AND  RELATED  FOEMS 


76.  Crustaceans.  —  The  Crustaceans  (krus-ta/ shuns  : 
Latin,  crusta,  crust)  are  so-called  because  of  their  hard 
outer  covering.  They  belong  in  the  same  group  of  ani- 
mals as  the  insects  and  are  more  highly  developed  than 
the  worms.     The  body  consists  of  a  limited   number  of 

segments,  each  of  which  usually  bears 
a  pair  of  jointed  appendages.  The 
appendages  are  variously  modified  ; 
some  aid  in  swimming,  others  in 
securing  food,  and  others  are  used 
in  walking.  The  jointed  appendage 
is  the  characteristic  expressed  in 
the  technical  name  Arthropoda  (iir- 
throp'o-da  :  Greek,  arthros,  joint  ; 
pod,  root  of  pous,  foot)  given  to  the 
group  to  which  all  these  animals 
belong. 

77.  Crayfish.  —  As  a  typical  crus- 
tacean we  have  the  common  crayfish, 
or  "  crab  "  as  it  is  known  away  from 
the  seashore.  The  crayfish  has  nineteen  pairs  of  append- 
ages adapted  to  different  kinds  of  work.  It  lives  in  fresh- 
water ponds  and  streams  where  there  is  sufficient  lime  for 
its  use  in  building  up  its  outside  covering  (exoskeleton). 

The  animal  is  divided  into  two  regions,  the  head-thorax 
region  and  the  abdomen.     The  segments  of  the  abdomen 

86 


Figure  83.  —  Crayfish 
bearing  Eggs. 


LIFE   HISTORY 


87 


are  clearly  defined,  but  tlio.se  of  the  head-thorax  are  so 
fused  that  they  cannot  be  made  out.     The  appendages  of 


Figure  84.  —  Crayfish. 


the  head-thorax  region  are  the  most  important  to  the 
animal.  Certain  of  these  are  fin-like  and  by  their  constant 
waving  motion  serve  to  carry  food  to  the  mouth.  Others 
are  elongated  and  serve  for  walking.  One  pair,  the 
pinchers,  are  used  for  seizing 
and  holding. 

The  last  abdominal  segment 
and  the  appendages  next  to  the 
last  are  broad  and  fin-like  and 
together  form  a  tail  fin  (caudal 
fin)  for  use  in  thrusting  the 
animal  backward,  when  it  is 
alarmed. 

78.  Life  History.  —  The  sexes 
are  distinct.  The  males  may  be 
distinguished  from  the  females 
by  the  larger  tubular  appendages 
on  the  first  and  second  segments 
of  the  abdomen.  The  egr^s  of  the  female  are  carried  for 
some  time  by  the  appendages  of  the  abdomen,  where  they 
pass   through    their   early  stages   of   development,.     The 


Figure  85.  —  Molted  Exo- 
skeleton  of  lobster. 


88 


CRUSTACEANS 


young  crayfish  is  unlike  the  adult  in  form,  and  approaches 
maturity  only  after  passing  through  many  changes 
(Figure  84). 

79.  Molting.  —  One  of  the  interesting  features  in  the 
study  of  the  crayfish  is  the  shedding  of  the  external  skele- 
ton. Being  covered  by  a  firm  exoskeleton  it  is  necessary 
that  this  be  removed  occasionally,  in  order  that  the  animal 
may  grow.  Molting,  in  the  case  of  the  crayfish,  is  a 
serious  and  dangerous  operation,  as  it  is  followed  by  a 
period  during  which  the  crayfish  is  without  means  of 
offense  or  defense.  The  crayfish  usually  hides  until  a  new 
exoskeleton  is  partially  formed.  In  the  molting  process 
the  covering  of  the  eyes  and  part  of  the  lining  of  the  diges- 
tive tract,  as  well  as  the  whole  exoskeleton,  are  shed. 
The  crayfish  molts  every  year  of  its  life  and  several  times 
during  the  first  year  (Figure  85). 

LABORATORY   STUDY 

Place  several  crayfish  in  jars  or  aquaria  and  observe  their  behavior. 
Fill  out  the  following  report : 


DO    THEY 

Move  the 
Antenn.e? 


DO    THEY 

Walk 
Forward  ? 


Do  THEY 

Walk 

Backward  ? 


Do  they  Use 
Caudal  Fin  ? 


Do  THEY 

Move  Eyes  ? 


What  Organs 
Make  a  Cub- 
rent  in 
Water  ? 


Laboratory  study  on  the  appendages.  Examine  more  fully  than  in 
the  above  and  report  the  work  of  each  pair  of  appendages.  Compare  one 
of  the  abdominal  appendages  with  those  used  in  walking  and  feeling.  What 
is  the  work  of  the  large  pinchers  ?  How  many  fin-like  appendages  are 
found  in  the  mouth  region  ?  Notice  that  one  of  the  mouth  appendages 
has  a  flat  part  that  extends  in  front  of  the  gills.  This  part  of  the  append- 
age is  called  the  gill  scoop  or  bailer. 


DIGESTIVE  SYSTEM 


SI) 


80.  Food  and  Food-getting.  —  The  food  of  the  crayfish  is 
both  plant  and  animal,  living  and  dead.  One  of  the  simple 
water  plants,  Chara  (ka/ra),  furnishes  the  crayfish  with 
lime  for  its  skeletons.  Shells  of  snails  and  their  own 
shed  skins  also  help  to  supply  lime.  Crayfish  seize  food 
with  their  pinchers  and  move  it  towards  the  mouth.  Small 
food  particles  are  also  carried  towards  the  mouth  by  cur- 
rents of  water  produced  by  the  mouth  parts  and  the  ab- 
dominal appendages.  Particles  of  food  are  torn  loose  by 
the  teeth  or  mandibles. 

81.  Digestive  System. — The  mouth  is  just  back  of  the 
teeth,  and  connects  with  the  stomach  by  a  short  esophagus. 


Figure  86.  —  Organs  of  Crayfish. 


The  stomach  is  divided  into  front  and  back  parts.  The 
front  part  possesses  a  grinding  structure  known  as  the 
gastric  mill,  which  serves  to  shred  and  crush  the  food  and 
make  it  ready  for  digestion  in  the  back  part.  The  liver. 
or  digestive  gland,  pours  a  fluid  into  the  stomach,  which 
prepares  the  food  for  absorption  by  the  walls  of  the  stom- 
ach and  intestines.  The  intestine  begins  at  the  back  end 
of  the  stomach  and  extends  to  the  last  segment. 


90  CRUSTACEANS 

82.  Respiration.  —  Crayfish  obtain  oxygen  from  the  water 
by  means  of  gills  which  are  well  covered  by  the  overhanging 
skeleton  of  the  head-thorax  region,  but  are  really  outside 
of  the  body.  Most  of  the  gills  are  plume-like  in  shape 
and  are  attached  to  the  appendages,  but  some  of  them  are 
attached  to  the  thorax.  Water  is  made  to  circulate  through 
the  gill  chamber  by  means  of  the  gill  scoop  or  bailer.  The 
finely  branched  gill  affords  a  large  amount  of  surface  for 
the  absorption  of  oxygen. 

83.  Circulatory  System.  —  The  crayfish  has  a  well-devel- 
oped heart  from  which  extend  several  arteries-  that  carry 
blood  to  the  various  parts  of  the  body.  The  blood  returns 
to  the  heart  through  veins  and  through  several  irregular 
ducts  called  sinuses  (si'-nus-es).  As  the  blood  flows 
through  the  body  it  loses  oxygen  and  receives  carbon 
dioxide.  Fresh  oxygen  is  absorbed  by  means  of  the  gills 
which,  at  the  same  time,  pass  off  carbon  dioxide  from  the 
blood  into  the  water. 

84.  The  Nervous  System.  —  In  the  crayfish  this  is  made  up 
of  a  brain,  ventral  nerve  chain,  and  many  nerves.  The 
eyes  are  borne  on  a  pair  of  short  movable  stalks.  The 
special  senses  are  well  developed,  and  the  sense  of  taste  is 
keener  than  that  of  most  lower  animals. 

85.  Excretion.  —  The  organs  for  excretion  of  waste  are 
the  green  glands  that  are  found  at  the  base  of  the  antennas. 
Blood  going  to  these  glands  loses  some  of  the  waste  which 
it  has  gained  in  its  course  through  the  body.  The  method 
of  purification  of  the  blood  in  these  glands  is  much  the 
same  as  in  the  kidneys  of  the  higher  animals. 

86.  Other  Crustaceans.  —  Shrimps,  lobsters,  and  crabs  are 
crustaceans  of  much  economic  importance,  because  of  their 
food  value.  The  trade  in  these  animals  amounts  to  millions 
of  dollars  each  year.  In  order  that  these  important  food 
animals   may    not  become  exterminated  by  careless  and 


ARACHNIDS 


91 


excessive  fishing,  the  state  and  national  governments  have 
attempted  to  control  the  numbers  taken  and  have  also 
established  hatcheries  in  which  the  eggs  are  hatched  and 
the  young  protected  dur- 
ing the  earliest  stages 
of  their  development. 

Crustaceans  of  less 
economic  importance 
are  the  barnacles  which 
cling  to  rocks,  wharves, 
and  steamships  ;  the 
hermit  crabs  that  live  in 
the  shells  of  mollusks 
(mol'lusks);  and  the  smaller  fresh-water  crustaceans  such 
as  the  Cyclops  (sl'klops),  Daphnia  (daf'ni-a),  and  Cypris 
(si'pris)  which  are  barely  visible  to  the  unaided  eye. 


Figure  87. —  Soft-shell  Crab. 


Figure  88.  —  Pill 
Bug. 


Figure  89. — Cyclops. 


87.  Arachnids.  —  The  spiders,  scorpions  (skor'pi-iins), 
ticks,  and  mites  are  arthropods  that  are  grouped  together 
under  the  name  Arachnida  (a-rak'ni-da  :  Greek,  araehne* 
spider).  The  spiders  and  scorpions  have  eight  walking 
appendages.  The  forward  pinchers  of  the  scorpions  arc 
mouth-parts,  and  not  walking  appendages.     The  harvest- 


92 


CRUSTACEANS 


man  (daddy-long-legs)  is  a  harmless  arachnid  which  does 
good  by  destroying  injurious  insects.     The  spiders  catch 

insects  either  by  pounc- 
ing upon  them  or  by 
entangling  them  in  their 
webs.  Scorpions  sting 
severely,  but  the  wound, 
although  painful,  is  rarely 
fatal.  Some  ticks  and 
mites  are  parasitic  on 
man  and  beast. 

88.     Myriapods.  —  An- 

Figure  90.  -  Daddy-long-legs.  Other    group    of    arthro- 

pods is  the  Myriapoda 
(mir'i-a-po-da  :  Greek,  myrias,  many),  a  group  which  in- 
cludes   animals    of    many  legs    such    as    the    centipedes 


Figure  91.  —  Spider. 


Figure.  92. 

a.  Thousand-legged 
worm ;  b,  Centipede. 


(sen'ti-pedz)      and      "thousand-legged      worms."       The 
centipedes  are  provided  with  poison  glands,  and  their  bite 


SUMMARY  93 

is  fatal  to  some  of  the  smaller  animals  and  painful  to  man. 
The  thousand-legged  worms  are  harmless. 

Note.  Insects  have  been  studied  also  in  Chapters  I  and 
II,  but  it  should  be  remembered  that  they  are  arthropods. 

SUMMARY 

An  animal  belongs  to  the  arthropods  if  it  has  more  than 
two  pairs  of  appendages  which  have  several  joints  in  them. 
They  also  have  an  external  skeleton  which  is  shed  at 
irregular  intervals  in  order  to  allow  the  animal  to  increase 
in  size.  The  body  of  the  crayfish  shows  that  part  of  the 
segments  have  fused  to  form  the  head-thorax  region.  The 
members  of  this  group  vary  much  in  size  and  habits. 
Lobsters  and  crabs  are  valuable  for  food  and  for  this 
reason  should  not  be  caught  when  they  are  small. 

QUESTIONS 

What  kind  of  animals  belong  to  the  crustaceans  ?  How  can  you  dis- 
tinguish one  from  a  worm  ?  From  a  hydroid  ?  Explain  why  insects  are 
arthropods.  Which  groups  of  arthropods  are  beneficial  ?  Which  are 
harmful  ?  What  do  you  mean  when  you  say  that  an  insect  is  beneficial 
or  harmful  ? 

REFERENCES 
See  Chapter  II. 


CHAPTER    IX 

THE  MOLLUSKS 

89.  The  Mollusks.  —  This  group  includes  such  animals  as 
clams,  oysters,  snails,  slugs,  squids  (skwids),  and  octopi 
(6k't5-pi).  These  forms  differ  from  the  crustaceans  in 
having  a  soft,  unsegmented  body  and,  in  most  cases,  a 
shell  as  their  exoskeleton.  The  squids  have  a  shell  that 
is  internal,  and  the  shell  is  absent  in  some  of  the  snails. 

90.  Clams.  —  The  fresh  water  clam  is  a  convenient  type 
of  mollusk  to  study.  It  is  found  in  canals  and  in 
many  streams  and  lakes.  This  clam  has  two  shells  or 
valves  and,  when  moving  naturally,  the  hinge  is  upper- 
most, while  the  opened  valves  allow  the  foot  to  be  ex- 
tended into  the  mud. 
The  foot  is  a  thick,  mus- 
cular mass,  not  at  all 
foot-like  in  appearance, 
but  it  enables  the  clam 
to  move,  although  slowly 
and  at  an  uneven  rate. 

91.  Structure.  —  The 
structure  of  the  fresh 
water  clam  shows  how 
it  has  adapted  itself  to 
its  peculiar  method  of  life.  The  shell  is  lined  with  a 
membrane  called  the  mantle.  The  mantle  secretes  the 
shell-material  and  adds  to  its  size  year  by  year.  At  the 
back,  the  edges  of  the  mantle  are  united  at  three  points, 

94 


Figure  93.  —  Clam  Showing  Foot. 

Water  enters  through  i.s.,  inhalent  siphon, 
and  leaves  the  body  of  the  clam 
through  e.s.,  exhalent  siphon. 


STRUCTURE 


95 


Showing  mantle  and  muscles,  a.a.  an- 
terior adductor  muscle ;  p. a,  pos- 
terior adductor  muscle. 


thus  forming  two  openings  known  as  siphons  (si 'tons). 
Through  one  of  these  siphons  water  enters,  carrying  food 
and  oxygen.  Through  the  other  the  water  passes  out, 
carrying  the  waste  from 
the  body. 

Between  the  mantle 
and  the  body  proper  are 
gills,  which  hang  free  in 
the  shell  cavity.  The 
gills  are  filled  with  holes 

through  which  the  water         Figure  94. —  Right  Shell  of  Clam 

passes. 

The  foot  is  attached 
directly  to  the  body 
proper  and  is  the  part  of  the  clam  hard  to  chew  when  it 
is  eaten.  The  foot  and  body  form  a  solid  mass  that  nearly 
fills  the  space  between  the  shells. 

The  two  valves  of  the  clam  shell  are  held  together  by 
means  of  strong  muscles,  attached  to  each  shell.  One  of 
these  is  located  in  front  of  the  body  and  is  known  as  the 

anterior  (front)  adductor 
(ad-diik'ter)  muscle:  the 
second  is  just  back  of  the 
body  and  is  the  posterior 
(back)  adductor  muscle. 
When  these  two  muscles 
contract,  the  two  valves 
are  held  tightly  together. 
Before  the  live  clam  can 
be  examined  these  two 
muscles  have  to  be  cut,  as  it  closes  its  valves  when 
handled.  When  the  clam  is  dead,  these  muscles  relax  and 
the  hinge  forces  the  valves  apart.  It  is  not  safe  to  eat 
clams  and  oysters  that  have  died  in  their  shells. 


Figure  95.  —  Digestive  Tube  of  Clam 
m,  mouth ;    s,  stomach ;    i.c,  intestine. 


96  MOLLUSKS 

When  the  two  adductor  muscles  are  cut  free  from  the 
valves,  a  round  or  oval  surface  is  seen  which  is  marked  off 
from  the  rest  of  the  interior  of  the  shell.  These  areas 
are  called  muscle  scars  (Figure  94). 

When  the  empty  clam  shell  is  examined,  it  is  found 
that  the  hinge,  sometimes  called  the  hinge  ligament,  is 
elastic.  This  is  shown  by  compressing  the  two  valves  and 
seeing  how  promptly  they  open  when  the  pressure  is  taken 
off.  Where  the  two  valves  come  in  contact  just  beneath 
the  hinge  ligament,  a  blunt  projection  of  one  shell  fits  into 
a  depression  in  the  other.  These  are  called  the  hinge 
teeth. 

LABORATORY   STUDY 

Live  clams  can  be  secured  in  the  market  during  the  school  year.  The 
dissection  of  the  clam  is  too  difficult,  but  the  arrangement  of  the  organs 
in  the  mantle  cavity  can  be  studied.  The  position  of  the  adductor 
muscles,  foot,  gills,  palps,  heart,  etc.,  should  be  observed.  Examine  a 
small  portion  of  a  gill  under  the  microscope  for  cilia.  A  variety  of 
shells  of  clams  should  be  studied  in  which  hinge,  muscle  scars,  and  hinge 
teeth  are  examined.    Compare  clam  and  snail  shells. 

92.  Locomotion.  —  The  movements  of  the  fresh  water 
mollusks  are  extremely  slow.  In  the  clam  the  foot  is 
forced  out  of  the  shell  by  the  blood,  which  flows  into  it 
and  causes  the  foot  to  be  greatly  enlarged.  Muscles 
attached  to  the  shell  and  front  of  the  foot  contract  and 
pull  the  shell  forward  over  the  extended  foot. 

93.  Food. — The  food  of  the  clam  consists  of  microscopic 
plants  and  animals  that  .  are  caught  in  a  sticky  fluid 
(mucus)  on  the  gills,  as  the  water  passes  through  them. 
The  food,  together  with  the  mucus,  is  moved  into  the 
mouth  by  means  of  cilia.  The  mouth  is  simply  an  open- 
ing into  the  body  and  the  cilia  are  on  triangular  flaps  or 
lips  (palps)  on  either  side  of  the  mouth.  From  the  mouth 
food  passes  into  the  digestive  canal,  where  the  nutritious 
parts  are  absorbed  (Figure  95). 


-    .  " 

1 

■ 

N 

CIRCULATION  97 

94.  Respiration.  — The  clam,  like  other  aquatic  animals, 
gains  its  oxygen  from  the  water  and  gives  off  carbon 
dioxide.  A  close  inspection  of  the  mantle  shows  the  pres- 
ence of  blood  vessels  which  are  more  numerous  than  in 
the  gills.  For  this  reason,  the  mantle  is  regarded  as  the 
main  organ  of  respiration,  although  the  gills  also  assist. 

95.  Life  History. — In  clams  the  sexes  are  distinct.  Kggs 
formed  in  the  ovaries  of  the  female  fuse  with  sperm  cells 
from  the  males  taken  in  with  the  water  through  the 
siphon.     These  sperm  cells  have  reached 

the  water  through  the  upper  siphon. 
Thousands  of  embryos  form  in  the  body 
of  the  female  and  develop  into  larvse 
in  the  outer  gills  which,  thus  become 
greatly  distended.  Later  the  larvse 
pass  into  the  water  through  the  upper     FlGURoF96^MBRYO 

1  *  That  attaches  itself 

The  larvae  of  many  fresh  water  clams  to  a  fish. 

have  hooks  on  their  shells  and  by  means 

of  these  they  are  able  to  cling  to  the  gills  or  body  of  a 

fish,  where  they  live  as  parasites  for  several  weeks.     They 

absorb  food  from  their  host  and  are  carried  from  one  place 

to  another  and  are  thus  scattered.     After  a  few  weeks  they 

leave  the  host  and  settle  down  to  lead   an  independent 

life. 

96.  Excretion.  —  The  wastes  of  the  body  are  absorbed 
by  the  kidneys  and  passed  out  into  the  water  through  the 
upper  siphon. 

97.  Circulation  is  well  developed.1  From  the  heart  the 
colorless  blood  is  carried  through  arteries  into  smaller 
tubes,  and  returns,  through  veins,  back  to  the  heart. 


1  The  three  chambered  heart  lies  in  the  dorsal  region,  near  the  hinge,  in  a 
little   soft-walled    chamber,  the    pericardium  (pe"r-i-c&r'di-um :    Greek    peri, 

around;  cardia,  heart). 


98 


MOLLUSKS 


98.  The  Nervous  System  is  not  so  well  developed  as  in 
the  crayfish.  There  are  three  groups  of  ganglia  (nerve 
cells).  One  located  far  back  in  the  body  near  the  posterior 
adductor  is  called  the  visceral  ganglion  because  it  largely 
regulates  the  activities  of  the  viscera  (vis'se-ra),  the  inter- 
nal organs  of  the  body.  Another  in  the  foot  region  is 
called  the  pedal  (pe'dal)  ganglion,  and  regulates  the 
movements  of  the  foot.  A  third  located  in  the  region  of 
the  gullet  (esophagus)  is  the  cerebral  ganglion,  which 
regulates  the  activities  of  the  part  near  the  mouth.  All 
of  these  are  connected  by  nerves. 

99.  Digestive  System.  —  The  mouth,  which  is  located 
under  the  anterior  adductor  muscle,  leads  through  the 
short  esophagus   to  the   stomach.      The    intestine   winds 

through  the  foot  region  forming 
a  loop,  finally  ascending  and 
passing  through  the  pericardium 
and  between  the  chambers  of  the 
heart  itself  and  opening  into  the 
upper  siphon  (Figure  96). 

100.  Snails.  —  Snails  having  one  valve  are  called  uni- 
valves as  distinguished  from  clams,  oysters,  etc.  which 
are  called  bivalves  because  their  shells  are  formed  of  two 
valves.  The  greater  number  of  snails 
are  marine  (live  in  salt  water),  although 
some  live  in  fresh  water  and  some  on 
land.  Snails  have  a  broad  foot  which 
is  used  as  a  creeping  disk.  There  is 
a  head  region  provided  with  eyes  and 
tentacles.  The  mouth  of  the  snail  is 
provided  with  a  rasping  structure  known 
as  the  lingual  ribbon  (lin'gwal :  Latin, 
lingua,  tongue)  by  means  of  which  it 
is  able  to  cut  and  bore  its  way,  even 


Figure  97.  —  Snail. 


Figure  98. — Tongue 

of  Snail. 

(Magnified.) 


SQUIDS,   CUTTLE   FISH,   AND  OCTOPl 


99 


through  rocks.  Land  snails  by  osmosis  get  oxygen  from 
the  air  through  the  mantle,  while  water  snails  use  gills 
and  take  their  oxygen  from  the  water. 


Figure  99.  —  Snail  Shells. 

In  the  garden  slug  the  shell  when  present  is   thin  and 
affords  small  protection. 

101.  Squids,  Cuttle  Fish,  and  Octopi  belong  to  the  Cephalo- 
pods  (sefa-lo-pods  :  Greek,  kephale,  head  ;  pod,  foot),  the 
highest  division  of  the 
mollusks.  The  nervous 
system  is  highly  devel- 
oped. The  eye  of  the 
squid  in  particular  is 
complex  and  more  like 
the  eye  of  vertebrates 
than  of  any  animal  thus 
far  considered.  The 
mouth  of  cephalopods  is 
surrounded  with  ten- 
tacles. 

A     common     squid,  Figure  100. — An  Octopus. 


100 


MOLLUSKS 


Sepia  (se'pi-a),  has  ten  arms  or  tentacles,  two  long  and 
eight  short.  It  moves  itself  forward  rapidly  by  shooting 
out  water  from  a  siphon  in  the  collar  region.  When 
pursued,  the  squid  ejects  an  ink-like  fluid  which  clouds 
the  water,  concealing  it  from  its  prey  and  facilitating  its 
escape. 

Cuttle  fishes  are  similar  to  squids,  the  marked  differences 
being  in  the  shape  of  fins,  the  form  of  the  eyes,  and  the 
shape  of  the  longer  tentacles. 

The  octopi  are  the  largest  members  of  the  group.  They 
have  eight  tentacles,  which  in  some  cases  reach  a  length  of 
thirty  feet.  The  stories  about  the  size  and 
behavior  of  the  octopi  are  often  exaggerated. 
102.  Economic  Importance  of  the  Group.  — 
Clams,  scallops,  oysters,  and  snails  are  used 
as  food  in  all  parts  of  the  world.  In  this 
country,  oysters  are  gathered  in  great 
abundance  from  Chesapeake  Bay  and  other 
bays  along  the  Atlantic  Coast. 

The  edible  clams  are  of  two  kinds.  The 
round  clam,  Venus  mercenaria  (Ve'nus 
mer-se-na/ri-a),  is  more  generally  used  as 
food,  but  the  other  kind,  the  soft-shelled 
clam,  Mya  arenaria  (Mi'a  ar-en-a/ri-a),  is 
eaten  extensively  near  the  seashore.  The 
soft-shelled  clam  has  a  long  siphon  which 
may  be  extended  several  inches  beyond  the 
valves  (Figure  101). 

The  scallop  (skol'lup)  is  another  mollusk 
that  is  eaten  near  the  shore  more  extensively 
than  elsewhere.  This  mollusk  has  but  one  adductor 
muscle,  which  is  the  edible  portion. 

Clams  and  oysters  are  raised  artificially  and  regularly 
planted  on  natural  feeding  grounds.       Care  is  taken  to 


Figure  101. 

Soft-shell 

Clam. 

a,  b,  siphons;  m, 
mantle;  s,  shell; 
/,  foot. 


Jean  Louis  Rudolphe  Agassiz  was  born  in  Switzerland,  in 
1807,  and  died  at  Cambridge,  Massachusetts,  in  1873.  He  was 
especially  noted  for  his  work  in  geology  and  ichthyology  (the 
science  of  fishes). 

Agassiz  came  to  the  United  States  in  1846  on  a  scientific  expe- 
dition and  took  up  his  residence  here,  becoming  Professor  of 
Zoology  and  Geology  at  Harvard,  and  Curator  of  the  Museum  of 
Comparative  Zoology  at  Cambridge.  He  explored  the  Lower 
Amazon  in  1865-66.  In  1871-72  he  accompanied  the  Hassler 
expedition  to  the  South  Atlantic  and  Pacific. 

Few  have  done  more  than  Agassiz  to  popularize  science,  and 
few  teachers  have  trained  so  many  young  and  rising  naturalists. 


ECONOMIC  IMPORTANCE 


101 


have  such  natural  enemies  as  the  starfish  removed,  and,  in 
the  case  of  oysters,  brush  and  shells  are  added  that  they 


- 


': 


\ 


w  Vi?  ■ 


ffmm 


> 


- 


\ 


- 


■ 


\         I         •       V.  \ 


Figure   102.  —  Stages  in  Life  History  of  Oyster. 

may  fasten  to  these  rather  than  sink  to  the  bottom,  where 
they  become  covered  with  mud.  . 

The  culture  of  oysters  and  clams  near  the  mouths  of 
rivers  contaminated  with  sewage  is  unsanitary,  and  dis- 
ease may  be  caused  by  eating  such  mollusks  raw.      This 


Figure  103. —  Barnacles  and  Clams  Growing  on  Oysters. 


102  MOLLUSKS 

is  one  reason  for  the  laws  regulating  the  disposal  of  sewage, 
and  for  government  inspection  of  the  feeding  grounds. 

SUMMARY 

The  parts  of  mollusks  are  not  arranged  in  segments 
like  the  earthworms  or  crustaceans.  The  usual  presence 
of  a  shell  and  mantle  and  the  fact  that  the  soft  body  is 
not  divided  into  segments  helps  to  distinguish  a  mollusk 
from  any  other  animal.  The  microscopic  food  of  the 
clam  is  caught  in  the  mucus  and  carried  by  cilia  to  the 
mouth.  The  clams  and  oysters  are  valuable  for  food  but 
should  not  be  eaten  if  taken  from  water  contaminated  by 
disease  germs.  Mollusk  beds  should  be  protected  from 
such  contamination. 

QUESTIONS 

What  are  some  of  the  common  mollusks  ?  Where  do  they  live  ? 
How  do  they  get  their  food  ?     What  ones  are  used  for  food  by  man  ? 

REFERENCES 

Brooks,  The  Oyster. 
Cambridge  Natural  History,  Vol.  III. 
Kellogg,  The  Shellfish  Industries. 
Linville  and  Kelly,  Zoology. 


CHAPTER   X 

PISHES 

103.  Vertebrates.  —  All  of  the  animals  thus  far  studied 
are  grouped  together  under  the  name  of  Invertebrate*. 
because  they  have  no  backbone.  We  are  now  to  study 
the  Vertebrates,  animals  with  a  backbone,  such  as  fishes, 
frogs,  snakes,  and  birds. 

The  presence  of  a  backbone  in  vertebrates  is  their  most 
conspicuous  characteristic.  The  formation  of  the  back- 
bone is  always  preceded  by  the  growth  of  an  embryonic 


Figure  104.  —  Skeleton  of  Fish. 
Note  backbone. 

group  of  cells  that  do  the  work  of  a  skeleton.  This 
embryonic  group  of  cells  forms  a  structure  which  is  called 
the  notocliord  (no'to-kord  :  Greek,  notos,  back;  chorda, 
cord).  In  all  of  the  true  vertebrates  (such  as  fishes, 
frogs,  etc.),  the  notochord  is  gradually  absorbed  and  the 
backbone  takes  its  place,  but  between  the  vertebrae  it 
remains  as  cushions.     But  in  the    fish-like  animal   railed 

103 


104 


FISHES 


Figure  105.  —  Perch. 


Amphioxus  (am-fi-oks'us),  the  notochord  persists  and 
there  is  never  a  true  backbone.  The  notochord  is  always 
found  above  the  food  tube  and  below  the  spinal  cord. 

Another    characteristic    common   to    all   vertebrates   is 
the  presence  of  gill-slits.     These  are  external  openings  on 


Figure   106.  —  Sunfish  or  Pumpkin  Seed. 


VERTEBRATES  105 

each  side  of  the  neck  that  in  the  fishes  allow  the  water  to 
pass  over  the  gills.  Such  structures  are  of  use  only  to 
aquatic  animals,  and  yet  all  vertebrates  have  them  at  some 
time  in  their  development. 

In  most  vertebrates  the  skeleton  is  composed  of  bone. 
There  are  usually  two  pairs  of  appendages  (legs,  wings, 
or  fins)  attached  to  the  body  at  the  shoulder  and  hip. 
Here  special  bones  join  the  limb  to  the  body.  The  bones 
in  the  shoulder  are   known  as  the  pectoral  (pek't6-ral) 


Lr    ^ 

1/   ' 

■  *^^ 

* 

J#*-^>, 

P^^^ 

HH| 

%# 

"V^^ **j     •'   \ 

s*  * 

K,m      ;.                             -V 

*"&:'-*>  *T    *5T 

Figure  107.  —  Catfish,  Bullhead,  or  Horned  Pout. 

girdle ;  while  those  in  the  hip  are  termed  the  pelvic 
(pel'vik)  girdle.  In  the  snakes,  only  traces  of  legs  are 
found  (Figures  104,  139,  and  158). 

A  further  distinguishing  feature  of  all  vertebrates  is 
the  well-developed  nervous  system,  with  its  large  brain. 
The  sense  organs,  eyes,  ears,  and  the  like,  are  also  better 
developed  than  in  any  of  the  invertebrates. 

Oxygen  is  obtained  by  external  or  internal  gills  in  most 
aquatic  animals  and  by  lungs  in  all  other  vertebrates.  In 
many  vertebrates  the  skin  is  an  active  agent  in  the  inter- 


106  FISHES 

change  of  oxygen  and  carbon  dioxide  and  particularly  in 
those  animals  which  have  a  thin,  moist  skin  like  frogs. 

104.  Fishes.  —  The  fishes  are  vertebrates,  that  is,  they 
have  a  notochord  which  as  they  develop  gives  place  to  a 
vertebral  column.  There  are  four  large  divisions  of  fishes 
(1)  the  lampreys  (lam'priz)  and  relatives,  (2)  the  sharks 
and   relatives,   (3)  the   bony   fishes,    and    (4)  the   small 


1 

'2~-T~~*i'mw 

^Vj|S  BwSjI&ftj^^ 

- ; -*2— ! - : A L 

Figure  108.  —  Brock  Trout. 

group  of  fishes  with  lungs.  The  most  important  group 
in  numbers  and  economic  importance  is  the  bony  fishes. 
This  group-  includes  the  salmon  (sam'un),  trout,  bass, 
whitefish,  pike,  shad,  menhaden  (men-ha/d'n),  cod,  mack- 
erel, herring,  sardine,  etc.  Typical  bony  fishes  are  the 
goldfish,  perch,  and  sunfish  (Figures  105-108). 

105.  External  Parts  of  a  Fish.  —  The  external  parts  of  a 
fish  show  a  well-marked  head  attached  directly  to  the 
trunk  ;  a  trunk  region,  the  largest  part  of  the  body  ;  and 
a  tail  region  which  is  sometimes  as  long  as  the  trunk. 

In  a  bony  fish  the  mouth  is  at  the  front  end  of  the 
head.  The  jaw  bones,  bearing  many  small,  needle-like 
teeth,  are  not  firmly  attached  to  the  skull.     The  side  of 


EXTERNAL   PARTS 


107 


the  head  next  to  the  trunk  is  protected  by  a  piece  of  bone 
that  covers  the  gills  (gill  cover  or  operculum,  6-peV- 
ku-liim),  and  the  openings  leading  into  the  nostrils,  which 
do  not  connect  with  the  mouth  cavity. 

The  trunk  bears  a  number  of  fins.  Each  fin  is  fur- 
nished with  several  bony  fin-rays  covered  by  a  thin  fold 
of  skin.  On  the  shoulder  and 
hip  regions  of  the  trunk,  the 
fins  occur  in  pairs  and  are  called 
the  pectoral  and  pelvic  fins. 
Several  fins  are  found  that  are 
not  in  pairs.  These  are  the 
median  fins  of  the  trunk. 

The  caudal  or  posterior  re- 
gion of  the  fish  ends  in  a  large 
median  fin.  The  tail  region  is 
chiefly  important  in  locomotion, 
but  the  fins  also  help  in  balanc- 
ing and  steering. 

Scales  cover  the  trunk  and  tail,  each  one  overlapping 
like  the  shingles  of  a  house.  The  skin  is  full  of  mucous 
glands  that  keep  the  fish  covered  with  slime.  Both  the 
slime  and  the  scales  protect  the  fish  (Figure  109). 


Figure   109.  —  Scales  of 
Fishes.     (Magnified.) 


LABORATORY   STUDY 

Study  living  fish  such  as  goldfish  or  perch.     Place  one  or  two  in  an 
aquarium  and  observe  their  behavior.     Fill  out  the  report  below. 


Number 

Number  of 

Paired 

Fins 

Number  of 

Unpaikkd 
Fins 

Which    \i:k    I  -i  D    i" 

I><>  the 

of  Fins 

Advance  ? 

Stop  ? 

Balance  f 

\'.\  bsMovi  ! 

108  FISHES 

Note  the  shape  and  relative  position  of  the  head,  trunk,  and  tail  region. 
The  gills  are  covered  by  a  bony  shield,  the  operculum.  What  is  its  size 
and  how  attached  ?  Where  are  the  eyes  located  ?  Do  they  move  ?  Can 
the  eyes  be  closed  ?  How  is  the  body  covered  ?  Of  what  use  is  this 
covering  to  the  fish  ? 

106.  Respiration.  —  Water  is  taken  in  through  the  mouth 
and  passes  out  through  two  openings,  one  on  each  side 
of  the  neck.  In  each  opening  four  or  five  gills  are  found. 
The  gills  are  made  up  of  numerous,  small,  very  short, 
fleshy  threads  or  filaments.  Into  each  filament  a  blood 
vessel  penetrates  and  here  the  blood  throws  off  carbon 
dioxide  and  takes  oxygen  from  the  water  by  osmosis  just 
as  the  blood  of  the  crayfish  does.  The  thin-walled  gill- 
filaments  are  adapted  to  respiration  in  the  water.  The 
water  is  drawn  into  the  mouth  and  forced  out  over  the 
gills,  in  much  the  same  way  as  water  is  pumped  from  a 
well.  When  a  fish  opens  its  mouth,  the  water  rushes  in. 
As  the  mouth  is  closed,  the  floor  of  the  mouth  and  throat 
is  raised  slightly,  pushing  the  water  against  the  side  of 
the  neck  and  through  the  gill  opening.  The  mouth  is 
thus  emptied  of  water  so  that  when  it  is  opened  again 
more  water  flows  in. 

107.  Food  Taking.  —  Fishes  eat  insects,  worms,  crayfish, 
snails,  and  other  fish.  The  teeth  of  fish  serve  to  seize,  tear, 
and  hold  food.  None  of  the  fish  have  teeth  which  are 
adapted  to  crushing  or  chewing  the  food,  as  is  the  case 
among  the  higher  vertebrates,  like  the  dog,  horse,  and 
man. 

Fishes  which  eat  minute  animals  and  plants  have  many 
sharp  pointed  projections  on  the  inside  of  the  gill  arches 
which  act  as  strainers  and  gather  quantities  of  this  small 
food  as  the  water  passes  over  the  gills.  These  projections 
are  called  gill-rakers.  Their  development  seems  to  vary 
in  proportion  as  they  are  needed  for  service.  Fishes  that 
feed  on  crayfish  and  on  small  fish  have  no  use  for  gill 


REPRODUCTION  109 

rakers  or  strainers  and   accordingly  their  gill  rakers  are 
undeveloped. 

108.  Special  Senses.  —  The  eye  is  well  developed.  It  is 
globular  and  projecting,  and  is  believed  to  be  near-sighted. 
The  organs  of  smell  are  usually  located  in  the  nasal  cavity. 
In  the  bull-head,  they  are  found  in  the  feelers,  on  the  head, 
and  even  in  the  skin  of  the  tail.  The  ear  is  under  the  skin, 
and  there  is  no  external  opening.  As  water  conducts 
sound  vibrations  more  readily  than  air,  no  device  for 
gathering  sound  waves  is  necessary. 

109.  Circulation.  —  The  blood  of  fishes  is  carried  in  well- 
defined  blood  vessels  and  a  heart  of  two  chambers.  The 
blood  is  sent  from  the  heart  to  the  gills,  where  it  is 
purified  of  carbon  dioxide  and  receives  oxygen.  It  is  then 
carried  by  means  of  arteries  to  other  parts  of  the  body, 
where  the  oxygen  in  turn  is  given  up  and  carbon  dioxide 
is  received.  The  blood  from  the  gills  and  other  parts  of 
the  body  is  returned  to  the  heart  through  veins.  Because 
the  blood  of  fishes  is  at  a  lower  temperature  than  the  blood 
of  man,  they  are  called  cold-blooded  animals. 

110.  Reproduction.  —  The  sexes  of  fish  are  distinct.  At 
certain  seasons  many  fish  migrate  upstream  to  lay  their 
eggs  (to  "spawn").  Eggs  are  laid  in  large  numbers  by 
the  females,  and  in  the  same  locality  sperm  cells  are  dis- 
charged into  the  water  by  the  males.  The  sperms  unite 
with  the  eggs.  The  fertilized  eggs  hatch  after  thirty  or 
forty  days,  or  longer,  depending  on  the  kind  of  fish  and 
the  temperature  of  the  water.  The  yolk  of  the  eggs  is 
attached  to  the  young  fishes 'for  many  days  after  they  arc 
able  to  swim,  and  they  need  no  other  food  than  that  sup- 
plied by  this  yolk  (Figure  111). 

The  spawning  habits  of  fish  must  be  understood  thor- 
oughly if  they  are  to  be  raised  artificially,  as  is  done  in  the 
many  fish  hatcheries.      Most  states   have  scientific   game 


110  FISHES 

laws  which  protect  the  fish  during  their  egg-laying  period 
when  they  are  easily  caught  and  when  the  destruction  of 
even  a  few  fish  means  the  loss  of  thousands  of  eggs. 

Spawning  habits  vary  greatly.  Some  fish,  like  the  sal- 
mon, make  long  journe}rs  from  the  sea  to  4;he  head  waters 
of  rivers  and  streams  to  deposit  their  eggs.  The  Colum- 
bia River  is  famous  for  the  number  of  salmon  which  spawn 
there.  Other  fish,  like  shad,  go  up  a  river  only  a  short 
distance  to  lay  their  eggs.     Many  shad,  for  instance,  go 


Figure  110.  —  Eggs  of  Land-locked  Salmon. 

up  the  Hudson  River  in  New  York  state.  In  the  case  of 
herring,  the  eggs  are  laid  in  the  sea  and  float  on  the  sur- 
face. Eels  go  down  from  the  rivers  and  streams  to  the 
sea  to  lay  their  eggs,  the  young  eels,  when  small,  migrat- 
ing up  the  river.  Millions  of  small  eels  no  larger  than 
needles  are  found  in  the  Hudson  at  certain  seasons. 

111.  Fish  Hatcheries.  —  In  the  natural  state,  many  eggs 
are  laid  that  never  hatch  because  the  sperm  cells  do  not 
come  in  contact  with  them,  and  of  the  fishes  that  are 
hatched  only  a  small  proportion  reach  maturity.  As  it  is 
a  matter  of  great  economic  importance  that  fishes  be  saved 
from  extermination  and  their  numbers  largely  increased, 


FISH   HATCHERIES 


111 


the  governments  of  the  world  have  established  hatcheries 
where  fish  are  raised  in  great  numbers. 

In  these  hatcheries  the  eggs  are  taken  from  the  female 
and  placed  in  a  jar,  and  the  mass  of  minute  sperm  cells  or 
"milt"  is  taken  from  the  male  and  poured  over  the  eggs, 


Figure  111.  —  Young  Fish  Showing  Yolk  Sac. 

so  that  practically  all  the  latter  hatch.  Then  by^  giving  the 
developing  eggs  protection,  and  the  young  fish  sufficient 
and  proper  food,  nearly  all  of  these  eggs  develop  into 
active  fish  and  the  great  loss  that  comes  to  the  fish  develop- 
ing in  their  natural  environment  is  prevented.  When 
they  are  able  to  take  care  of  themselves,  these  fry,  as  the 
young  hatchery  fish  are  called,  are  taken  to  natural  feed- 
ing grounds.       In  New  York  state  and  most  other  states 


pKppg 


Figure  112.  —  Young  Fish  Fry. 

there  are  state  hatcheries  where  such  fish  as  shad,  pike, 
lake  trout,  salmon,  brook  trout,  and  others  are  raised  by 
millions. 

The  fish  that  are  most  useful  as  food  are  taken  by  hooks, 
nets,  and  seines,  under  certain  restrictions.  Those  like 
brook  trout  which  are  caught  as  much  for  sport  as  for  food 
can  be  taken  only  by  a  hook  and  line  and  in  certain  seasons; 


112  FISHES 

the  season  of  the  year  depending  upon  the  time  of  spawn- 
ing. The  brook  trout  spawns  in  August  and  September, 
while  the  rainbow  trout  does  not  spawn  until  February  or 
March. 

112.  Care  of  Young.  —  Some  fish,  like  the  sticklebacks, 
build  nests  of  sticks  and  leaves  in  which  the  eggs  are 
placed  and  guarded.  Bass  and  sunfish  make  a  circular 
depression  several  feet  in  diameter  near  the  shore  and  lay 
their  eggs  on  these  so-called  ubeds."  These  beds  are 
guarded  zealously  by  the  males,  who  drive  off  or  carry 
away  crayfish  and  small  fish  which  feed  upon  such  eggs. 
In  former  times  men  sought  for  these  "  beds "  and  by 
dropping  a  baited  hook  caught  the  bass  while  defending 
their  eggs.  Fortunately  this  practice  is  now  illegal. 
Generally,  adult  fish  pay  no  attention  to  their  young  and 
in  many  cases  they  devour  young  of  their  own  kind  as 
quickly  as  fish  of  other  sorts. 

SUMMARY 

The  term  vertebrate  is  given  to  all  animals  that  have  a 
backbone.  All  have  gill  slits,  either  while  young  or  as 
adults.  Fish  have  scales  and  breathe  by  means  of  gills. 
Their  eggs  are  usually  laid  in  the  water  and  receive  no 
care  from  the  parents.  A  few  fish  prepare  a  crude  nest 
which  they  guard. 

QUESTIONS 

What  are  some  of  the  structures  that  all  chordates  have  ? 

Why  is  the  word  vertebrate  used  ? 

What  are  the  common  fishes  near  your  home  ? 

What  ones  are  sought  for  food  ? 

What  is  being  done  to  keep  up  the  supply  of  fish  in  your  state  ? 

What  do  fish  eat  ? 

REFERENCES 

Fish  Manuals  of  the  U.  S.  Commission  of  Fish  and  Fisheries. 

Jordan,  Fishes. 

Jordan  and  Evermann,  American  Food  and  Game  Fishes. 


CHAPTER   XI 


AMPHIBIANS 


113.  Amphibians.  —  Frogs  and  toads  are  the  best  known 
animals  of  this  group  ;  but  here  belong  also  the  Sala- 
manders (sttl'a-man-ders),  frequently  miscalled  lizards  (see 
page  131).  The  Am- 
phibians (am-fiL/i-ans : 
Greek,  amphi,  double  ; 
bios,  life)  are  all  small, 
the  largest  one  found 
in  America  being  a 
salamander  (Crypto- 
branchus), 
rarely  more 
feet   long. 

Amphibian  is  used  to 
explain  the  habit  which 
frogs,  toads,  and  certain 

salamanders  have  of  spending  their  larval  (tadpole  stage) 
life  in  the  water  and  their  adult  life  on  land,  or  partly  on 
land  and  partly  in  the  water. 


which      is 

than    two 
This   term 


Figure  113. 


—  Some  Common  Sala- 
manders. 


LABORATORY   STUDY 

Place  one  or  two  frogs  or  toads  in  a  small  jar  or  box  and  observe  the 
points  mentioned  in  the  report  below. 


DO    THEY 

Wink? 


Can  tiiky 

Protect 

their  Eyes  ? 


How  Do  they 
I  .  i;t   An: ': 


Can   tiiky 

W  \  ik  F  Hop ? 


How  Do 

l  1 1  B  Y    8w]  M  J 


HOW  Do   THOT 

Uatoh  \  Y\.\  :• 


113 


114 


AMPHIBIANS 


Figure  114.  —  Common  Frog. 


114.  Frogs.  —  There  are  several  kinds  of  frogs,  one  of 
which,  the   leopard  frog,  is  found    generally   distributed 

throughout  the  United 
States.  It  can  be  recog- 
nized by  the  presence, 
on  the  dorsal  surface,  of 
many  brownish  or  green- 
ish spots,  edged  with 
white,  which  help  the 
frog  to  escape  the  notice 
of  his  enemies  as  he 
squats  among  the  water 
weeds.  These  colors 
form  rather  definite  bands  on  the  hind  legs,  though  there 
is  much  variation.  The  general  form  of  the  body,  the 
shape  of  the  head,  and  the  long  hind  legs  adapted  for 
jumping  are  much  the  same  in  all  frogs. 

LABORATORY   STUDY 

Compare  the  general  shape  of  fish  and  frog.  How  do  the  colors 
differ  ?  Show  how  the  legs  and  feet  are  adapted  to  the  way  the  frog 
lives.  Is  the  frog  sensitive  to  touch  in  various  parts  of  the  body  ? 
Examine  the  eyes.  Open  the  mouth  and  see  that  the  frog  can  draw  in 
its  eyes.  The  ear  membrane  is  on  the  side  of  the  head  back  of  the  eyes. 
Pass  a  probe  through  the  ear  membrane  of  a  dead  frog  and  see  where  it 
comes  out  in  the  mouth.  This  is  the  opening  of  the  Eustachian  tube. 
How  far  can  the  living  frog  see  ?  Notice  the  method  of  breathing.  See 
the  throat  move  up  and  down.  Hold  the  frog  under  the  water  and 
gently  rub  its  sides.  It  will  usually  croak.  Thus  we  can  prove  that  the 
frog  is  able  to  make  the  air  travel  from  his  lungs  to  his  mouth  and  back 
again  while  under  water. 

115.  Habitat.  —  Frogs  are  seldom  found  far  from  some 
pond  or  stream  and  they  are  usually  seen  on  the  bank. 
When  disturbed,  they  jump  into  the  water,  swim  to  the 
bottom,  stir  up  the  mud,  and  quietly  come  to  rest  a 
short   distance  from  the  place  where  they  entered.     As 


INTERNAL  STRUCTURE  115 

the  nights  in  the  fall  grow  cool,  frogs  make  ready  to 
spend  the  winter  in  a  state  of  inactivity.  During  the 
warmer  part  of  the  day,  they  may  be  seen  sunning  them- 
selves on  a  bank,  but  as  soon  as  ice  forms  on  the  water 
they  remain  on  the  bottom  or  become  buried  in  the  mud. 
The  lungs  are  emptied  of  air,  the  heart  beats  decrease,  and 
all  of  the  usual  living  processes  take  place  more  slowly. 
This  habit  of  passing  the  winter  in  a  state  of  inactivity 
is  known  as  hibernation  (hl-ber-na/shiin).  All  of  the 
amphibia,  reptiles  (Chapter  XII,  page  129),  and  several  of 
the  mammals  hibernate  during  the  winter. 

116.  Food.  —  Frogs  are  greedy  creatures  and  will  eat 
almost  any  animal  small  enough  to  be  swallowed,  such  as 
insects,  worms,  snails,  tadpoles,  and  small  frogs.  These 
are  caught  alive  and  when  in  motion. 

117.  Enemies.  —  As  the  frog's  hind  legs  are  considered 
a  delicacy,  man  is  the  worst  enemy  of  the  frog.  Next 
come  the  snakes,  birds,  and  fish.  The  leech  kills  frogs  by 
sucking  their  blood.  Fish  eat  many  of  the  tadpoles,  and 
strange  to  say,  some  water  beetles  eat  tadpoles  also. 

118.  Respiration.  —  Both  the  skin  and  a  pair  of  lungs 
serve  to  purify  the  blood  of  the  frog.  The  air  is  forced 
into  the  lungs  by  the  contraction  of  muscles  in  the  floor 
of  the  mouth.  Experiments  have  been  made  which  show 
that  the  frog  can  get  enough  oxygen  even  if  the  lungs 
are  missing.  In  this  respect  frogs  resemble  worms,  which 
use  the  skin  as  the  only  organ  of  respiration. 

119.  Internal  Structure.  —  A  study  of  the  parts  of  the  frog 
or  toad  should  be  made  for  two  reasons:  (1)  To  understand 
the  relative  positions  of  the  internal  organs  of  a  typical 
vertebrate;  (2)  to  help  explain  the  several  organs  of 
man  which  are  discussed  in  the  second  part  of  this  book. 

Digestive  Organs. — The  mouth  is  large.  Short  lips 
cover  the  short  teeth  in  the  edge  of  the  upper  jaw.     The 


116 


AMPHIBIANS 


tongue  has  two  fleshy  horns  at  the  back  end  and  is 
attached  by  the  front  end  to  the  floor  of  the  mouth 
(Figure  115).  The  frog  can  throw  its  sticky  tongue  over 
the  tip  of  the  lower  jaw  and  use  the  forked  end  to  catch 
insects  which  are  then  carried  into  the  back  of  the  mouth. 
Two  groups  of  little  curved  teeth  in  the  roof  of  the 
mouth  aid  in  preventing  the  escape  of  the  prey.  The 
food   is   swallowed    whole.       The    esophagus    (the    tube 


Figure  115.  —  Diagram  to  Show  Organs  of  Frog. 


connecting  the  mouth  cavity  and  stomach)  of  the  frog 
can  be  stretched  so  that  a  comparative^  large  animal  can 
be  swallowed.  There  is  no  sharp  limit  between  the  esoph- 
agus and  the  stomach,  which  is  a  long  spindle-shaped  sac 
(Figure  115),  larger  than  the  rest  of  the  digestive  tube. 

The  small  intestine  begins  at  the  back  end  of  the 
stomach  as  a  small  tube  which  makes  several  turns,  and 
finally  enlarges  into  a  region  called  the  large  intestine, 
the  last  part  of  which  is  termed  the  cloaca  (cl5-a/ca)  or 
common  sewer.  * 

Two   glands    of   importance    belong    to    the    digestive 


INTERNAL  STRUCTURE 


117 


organs 


•  the  liver  and  the  pancreas.  The  liver  is  a 
large,  dark-red,  three-lobed  organ  that  covers  the  ventral 
(lower)  surface  of  the  stomach.  The  pancreas  is  a 
whitish,  small,  irregularly  shaped  body  attached  between 
the  stomach  and  the  intestine.  Both  of  these  glands 
drain  into  the  intestine  just  beyond  the  stomach.  The 
bile  secreted  by  the  liver  is  at  first  collected  in  a  sac 
called  the  gall  bladder. 

All  of  these  parts  of  the  alimentary  canal  are  held  in 
place  by  a  thin  membrane  (the  mesentery,  mOVen-te'r-y), 
one  edge  of  which  is  attached  to  the  dorsal  wall  along  the 
line  of  the  backbone  and  the  other  to  the  stomach  and 
intestine.  A  small  gland  (the  spleen')  is  found  in  this 
mesentery.  The  spleen  has  no  duct  connecting  it  with 
any  other  organ  in  the  frog.  Blood  vessels  run  through 
the  spleen  and  scientists  believe  that  it  is  important  in 
making  new  blood  corpuscles. 

Lungs.  —  The  lungs  are  hollow  sacs  that  lie  back  of  the 
stomach,  one  on  each  side.  In  the  freshly  killed  animal, 
these  can  be  filled  with  air  by  inserting  a  blow-pipe  into 
the  windpipe  and  blowing  air  into  them.  The  empty 
lungs  are  about  as  large  as  the 
blunt  end  of  a  lead  pencil. 

Kidneys.  —  The  kidneys  are 
small  red  bodies  lying  close  to 
the  back.  Each  one  is  connected 
with  the  cloaca  by  a  minute  duct 
(ureter).  The  urinary  bladder 
is  attached  to  the  cloaca  (Fig- 
ure 116). 

Reproduction.  —  The  male 
frog  has  a  pair  of  spermaries 
(speYma-riz),  one  attached  to 
the  front  (anterior)  end  of  each  Figure  116. 


//   fat   bodies 


^•testis 


kidneu 


-unnogenital 
duct 


cloaca 


118 


AMPHIBIANS 


nerve  to  nose 
Olfactory  Lobe 

-    Cerebrum 


nerve 


to 


eye 


Thalamencephalic^ 
Medulla  ■-•- 


y 


Optic  Lobe 

Cerebellum 

"--Nerve  to  ear 

■  ..4th  Ventricle 

.  nerve  to  arm 


kidney  (Figure  116).  Each  spermary  is  yellow  in  color. 
The  sperms  escape  through  the  kidney.  In  the  female 
frog  ovaries,  sometimes  filled  with  eggs,  are  easily  seen. 
A  long,  closely  coiled  pair  of  oviducts  (6'vi-dukts)  opens 
in  front  near  the  forward  end  of  the  stomach  and  in 
the  back  into  the  cloaca.     The   eggs  break  through  the 

wall  of  the  ovary  and 
enter  the  oviducts.  As 
the  eggs  pass  down 
through  the  oviducts, 
they  are  coated  with  a 
jelly-like  covering  that 
swells  in  the  water. 
This  jelly  covering  pro- 
tects the  eggs. 

Nervous  Syste?n.  — The 
nervous  system  of  the 
frog  is  more  highly  de- 
veloped than  that  of  the 
earthworm.  It  consists 
of  a  central  part  enclosed 
in  the  backbone  and  cra- 
nium (braincase).  This 
central  nervous  system 
in  all  vertebrates  is  al- 
ways   found    above    the 

Figure  1 1 7.    -  Central  Nervous  System    digestive  tube,  and  is  di- 

op   Prop 

vided  into  the  brain  and 
the  spinal  cord,  from  which  numerous  nerves  arise  and 
extend  to  all  parts  of  the  body. 

The  parts  of  the  brain  are  the  same  as  in  man  and 
much  easier  to  study.  Beginning  at  the  front  (anterior) 
end  of  the  brain  the  parts  are  as  follows  (1) :  small 
olfactory  (61-fak'to-ry)  lobes,  which  are  not  sharply  marked 


nerve 
to  leg 


INTERNAL  STRUCTURE  119 

off  from  the  rest  of  the  brain,  and,  as  shown  in  Figure  117, 
connect  with  (2)  the  cerebral  (ser'e-bral)  hemispheres, 
which  are  oval  in  outline.  (3)  A  short  mid-brain  region, 
partly  covered  by  the  back  part  of  the  cerebral  hemi- 
spheres, connects  the  front  and  back  part  of  the  brain. 
(4)  Two  large  optic  lobes,  the  widest  part  of  the  brain, 
are  just  back  of  the  mid-brain.  (5)  The  cerebellum 
(se'r-e-bel'lum)  of  the  amphibians  is  small  and  easily  over- 
looked (Figure  117).  The  last  region  of  the  brain  is  the 
(6)  medulla  (me-dul'la),  which  is  occupied  by  a  large 
triangular  cavity  called  the  fourth  ventricle. 

The  work  which  each  of  these  regions  of  the  brain  does 
is  not  sharply  defined.  The  olfactory  lobes  receive  the 
smell  stimuli.  The  cerebral  hemispheres  control  muscular 
action.  When  the  latter  are  removed  the  frog  loses  all 
power  to  initiate  any  movement  and  will  sit  still  in  a  dry, 
warm  room  for  hours  unless  disturbed.  This  he  never 
does  when  the  cerebral  region  of  the  brain  is  uninjured. 
The  mid-brain  region  is  the  passageway  for  all  nerve-path- 
ways that  travel  to  and  fro  in  the  brain.  The  mid-brain 
and  optic  lobes  explain  to  the  frog  the  sight  stimuli.  In 
the  frog,  the  cerebellum  is  less  important  than  in  man  and 
is  poorly  developed.  The  medulla  gives  off  more  nerves 
than  any  other  region  of  the  brain.  Here  are  found  the 
nerves  to  the  face,  tongue,  ear,  heart,  and  lungs.  While 
there  is  a  great  difference  between  the  shape  of  the  parts 
of  the  brain  of  the  frog  and  those  of  man,  yet  the  work 
done  by  each  region  is  of  the  same  kind. 

The  brain  joins  the  spinal  cord,  and  there  is  no  external 
sign  to  indicate  where  one  begins  and  the  other  leaves 
off.  A  definite  number  (ten  pairs)  of  nerves  leave  the 
brain  proper  and  are  devoted  to  the  special  senses  of  the 
head  and  to  moving  the  muscles  of  the  throat  and  head. 
The  frog  has  ten  other  pairs  of  nerves  joined  to  the  spinal 


120  AMPHIBIANS 

cord  (Figure  117).     In  a  long  salamander  there  are  20  or 
30  pairs  of  nerves  on  the  spinal  cord. 

LABORATORY   STUDY 

In  connection  with  the  study  of  the  frog,  the  following  additional  lab- 
oratory work  should  be  done  in  order  that  the  several  organs  of  man 
which  are  discussed  in  Part  II  may  be  better  understood.  Frogs  that 
have  been  preserved  in  formalin  can  be  easily  dissected.  Examine  the 
digestive  organs  :  first  the  mouth,  then  the  esophagus,  stomach,  small 
and  large  intestine,  and  cloaca.  For  convenience,  the  liver  will  have  to 
be  removed.  The  pancreas  can  be  seen  as  a  small  whitish  structure  in 
the  loop  between  the  stomach  and  the  intestine.  The  spleen  is  a  round, 
red  organ  usually  found  near  the  large  intestine. 

A  pair  of  narrow  kidneys  lies  close  to  the  back  and  is  connected  by 
ducts  with  the  cloaca.  The  spermaries  are  found  attached  to  each  kid- 
ney near  the  front  end  and  the  sperm  cells  escape  to  the  exterior  by  the 
kidney  ducts.  In  the  female  frog  the  large  ovaries  occupy  most  of  the 
space  of  the  body  cavity.  A  pair  of  oviducts  opens  into  the  body  cavity 
just  back  of  the  stomach.  The  eggs  escape  from  the  ovary  into  the  body 
cavity. 

The  nervous  system  is  enclosed  in  bone  that  is  easily  removed  from  the 
dorsal  surface.  The  brain  should  be  studied  and  the  following  divisions 
recognized  :  cerebral  hemispheres  ending  in  front  in  the  olfactory  lobes, 
which  are  not  clearly  marked.  Just  back  of  these  the  two  large  roundish 
optic  lobes  which  are  attached  to  the  midbrain  (thalamencephalori) ,  thal- 
a-men-ceph'a-lon).  The  cerebellum  is  small,  and  the  medulla  passes  into 
the  spinal  cord  without  any  sharp  dividing  line. 

120.  Development.  —  Late  in  March  and  early  in  April 
the  frogs  gather  in  ponds  to  lay  their  eggs.  The  eggs  are 
surrounded  by  a  jelly-like  substance  which  holds  them 
together.  As  the  eggs  are  being  laid  by  the  female  frog, 
the  male  frog  spreads  a  large  number  of  sperm  cells  over 
the  whole  mass.  These  sperm  cells  make'  their  way 
through  the  soft  jelly  and  one  of  them  must  enter  each 
egg  or  it  cannot  grow  into  a  tadpole. 

As  soon  as  the  sperm  cell  enters  the  egg  (Figure  119),  it 
begins  to  change  from  a  solid,  pointed  body  into  a  round 
nucleus  which  is  so  much  like  the  nucleus  already  in  the 


DEVELOPMENT 


121 


egg  cell  that  none  but  experts  in  this  study  can  tell  which 
came  from  the  sperm  cell  and  which  from  the  egg  cell. 
These  two  nuclei  come  in  contact  and  unite,  leaving  but 


Figure  118.  —  Frog  Eggs. 

one  nucleus  in  the  egg  (Figure  119).  This  last  change  is 
fertilization,  which  is  defined  as  the  union  of  the  contents 
of  the  egg  and  the  sperm  nuclei.  After  this  union  is 
completed  the  egg  begins  to  divide  into  cells,  as  shown 
in  Figure  120,  and  finally  a  tadpole  is  grown. 


Eg'g  Nucleus     Sperm  cell  Egg'  Nucleus      Sperm  Nucleus         Fused  Nucleus 


Figure  119.  —  Diagram  Illustrating  Fertilization  in  Frog  Egg. 

As  soon  as  the  young  tadpole  hatches,  it  attaches  itself 
to  plants  and  lives  for  the  first  few  days  upon  the  food- 
yolk  within  its  own  body  ;  the  mouth  forms,  and  horny 
jaws  develop.      Then  the    tadpole   begins  to  feed  upon 


122 


AMPHIBIANS 


minute  plants  and  becomes  dependent  upon  its  own  skill 
to  get  food  and  escape  its  enemies. 

For  a  time  the   tadpole  breathes  through  gills.     Two 
sets  are  used.     The  first  ones  are  on  the  outside  of  the 

body  and  last  for  only 
two  or  three  days,  when 
internal  gills  form  in  the 
throat  and  the  tadpole 
breathes  much  like  a 
fish. 

121.  The  Tadpole  Be- 
comes a  Frog.  —  In  the 
growth  of  the  tadpole 
into  a  frog  the  hind  legs 
appear  first.  Later  the 
front  ones  begin  to  show  and  as  they  develop  the  tail  is 
gradually  absorbed.  While  these  external  changes  are 
going  on,  there  are  many  complicated  internal  changes 
taking  place ;  internal  gills  are  disappearing  and  lungs, 
nerves,  blood  vessels,  and  muscles  are  being  formed  to  give 


Figure  120.  —  Dividing  Egg  of  Frog. 


Figure  121.  —  Dividing  Egg  Becoming  a  Tadpole. 


the  new  legs  life  and  action.  The  internal  lungs  take 
the  place  of  the  gills  in  the  throat  before  the  legs  are 
fully  grown  and  such  tadpoles  can  breathe  only  air.  Ex- 
plain  in   Figure    122    which   tadpoles   breathe   by  lungs 


EVOLUTION 


123 


and  which  by  gills.  This  complicated  way  of  growing  into 
a  frog  is  called  metamorphosis  and  this  term  lias  the  same 
general  meaning  that  it  did  when  used  to  describe  tin; 
growth  of  insects  (page  16). 

The    tadpoles    of    leopard   frogs   become    small    frogs 
in   a   single   summer,  but  the   tadpoles   of  bullfrogs   and 


Figure  122.  —  Two  Stages  in  the  Development  of  Tadpoles. 

green  frogs  require  two  seasons  to  complete  their  develop- 
ment. These  latter  tadpoles  hibernate  in  the  mud  with 
adult  frogs  and  toads. 

122.  Evolution.  —  Evolution,  in  a  larger  sense,  is  the 
theory  or  belief  that  all  of  the  complex  animals  and  plants 
on  earth  to-day  developed  from  the  simpler  animals  and 
plants  of  many  generations  ago.  This  theory  tries  to 
prove  itself  through  the  careful  study  and  investigation 
of  the  relationships  between  animals  and  plants  of  the 
present  and  those  that  formerly  existed. 

The  study  of  the  changes  through  which  the  egg  of  the 
frog  grows  into  a  tadpole  and  then  into  a  frog  tells  us 


124 


AMPHIBIANS 


much  about  the  way  frogs  have  developed  from  fishes. 
The  tadpole  breathes  and  eats  like  a  fish ;  but  as  soon  as 
lungs  and  legs  are  formed,  it  breathes  and  eats  like  a  frog. 
This  same  study  of  the  tadpole  also  illustrates  how  ani- 
mals may  gradually  have  come  to  live  on  land.  In  the 
early  history  of  the  earth  there  were  hundreds  of  animals 
and  plants  which  are  no  longer  known  to  science.  The 
skeletons,  foot-prints,  and  whole  bodies  of  many  of  these 
are  preserved  in  the  rocks.  Such  remains  are  called  fossils. 
If  all  the  animals,  or  one  of  each  kind,  had  been  pre- 
served in  the  rocks,  it  would  be  easy  to  investigate  these 


Figure  123.  —  Fossil  Shells  of  Animals  now  Extinct. 

earlier  animals  and  their  relation  to  the  living  animals  of 
the  present.  But  in  our  information  there  are  great  gaps, 
which  we  are,  however,  gradually  bridging.  Apparently 
unrelated  animals  have  resemblances,  so  that  in  time  we 
may  come  to  see  that  all  animals  are  really  related  forms, 
varying  only  in  complexity  of  structure.  One  thing  that 
we  must  always  keep  in  mind  is  that  the  plants  and  animals 
which  live  now  are  but  a  small  fraction  of  those  which  have 
lived.  The  rocks  have  preserved  the  remains  of  only  a 
small  part  of  the  forms  of  the  past.     Many  of  the  records 


HEREDITY  125 

of  extinct  animals  and  plants  have  been  destroyed  by  decay 
and  heat  so  that  much  that  would  be  valuable  in  solving 
the  question  can  never  be  found. 

The  study  of  the  development  of  the  frog  also  illustrates 
two  other  general  subjects,  heredity  (he-red'I-ty )  and  en- 
vironment (en-vl'run-ment). 

123.  Heredity. — The  tendency  of  all  young  animals  to 
grow  and  live  like  their  parents  is  called  heredity  and  may 
be  defined  as  the  transmission  of  physical  and  mental  traits 
from  parent  to  offspring.  There  is  no  difficulty  in  recog- 
nizing the  new  frog  as  a  certain  kind  of  frog.  The  color 
markings  on  the  skin  are  like  those  of  the  parents;  it 
grows  to  about  the  same  size;  eats  the  same  kind  of  food, 
and  lives  in  the  same  region. 

Every  species  of  living  thing  is  able  to  produce  new 
forms  like  itself,  and  heredity  is  always  at  work  when 
new  plants  and  animals  are  being  produced.  Heredity  is 
best  thought  of  as  that  quality  of  living  matter  which  ex- 
presses itself  in  the  growing  plant  and  animal  by  making 
sure  that  it  resembles  its  parents.  Thus  heredity  deter- 
mines that  leaves  of  the  right  shape  and  size  occur  in  the 
proper  place  and  that  our  fingers  and  thumbs  grow  on  the 
end  of  the  arm  in  the  usual  way. 

There  has  been  much  study  of  the  question  of  heredity 
and  there  is  much  yet  to  be  learned.  However,  we  know- 
that  we  inherit  from  our  parents  and  grandparents,  our 
complexion,  the  color  of  eyes  and  hair,  our  size,  our  re- 
sistance to  disease,  our  mental  traits,  and  many  other 
characteristics. 

In  1865  Gregor  Mendel,  abbot  of  Briinn,  published  t la- 
results  of  experiments  made  with  peas,  which  showed  thai 
crossing  tall  and  dwarf  peas  resulted  in  all  the  offspring 
being  tall.  But  the  offspring  of  these  latter  (the  grand- 
children, so  to  speak,  of  the  original  peas)  might  be  cither 


126 


AMPHIBIANS 


tall  or  dwarf.  The  proportions  were  regular  and  the  re- 
currence of  tall  or  dwarf  peas  was  so  uniform  that  from 
these-  and  other  experiments  later  scientists  evolved  defi- 
nite laws  of  heredity,  known  as  the  Mendelian  Laws. 

A  detailed  statement  of  these  laws  is  beyond  the  prov- 
ince of  an  elementary  book,  but  it  is  now  well  established 
that  certain  traits  of  parent  plants  and  animals  are  repro- 
duced in  their  offspring  in  regular  and  definite  amounts 
and  proportions. 

124.  Environment.  —  This  word  is  used  in  two  ways. 
First,  it  refers  to  general  surroundings  such  as  tem- 
perature, moisture,  and 
seasons,  as  they  vary 
from  year  to  year ;  and 
secondly,  to  immediate 
surroundings.  The  frog 
responds  to  the  first  by 
hibernating  in  the  win- 
ter ;  while  the  second 
phase  of  environment 
may  be  illustrated  as 
follows :  the  tadpole  can 
live  only  in  water,  and 
if  the  pond  dries  up 
before  the  frog  stage  is 
reached,  the  environment 
has  been  unsuited  to  the 
tadpole.  This  often 
happens  when  the  eggs 
are  laid  in  a  temporary 
roadside  pond  which  evaporates  long  before  the  tadpole 
becomes  a  frog.  All  such  tadpoles  die  unless  they  are 
able  to  swim  to  some  other  body  of  water. 

The  birds  that  are  able  to  fly  avoid  hibernating  in  the 


Figure   124. — Tree  Frog. 
Notice  the  sticky  disks  at  end  of  toes. 


ECONOMIC   VALUE  127 

winter.  They  are  able  to  adapt  themselves  to  the  change 
in  the  seasons  without  burying  themselves  in  the  mud  as 
the  frogs  do. 

Some  of  the  birds  do  not  migrate,  but  remain  all  winter 
in  the  North.  They  have  become  so  well  adapted  to  con- 
ditions that  they  are  able  to  get  their  food  where  birds 
that  migrate  would  starve. 

Man  is  the  only  animal  which  is  able  to  live  anywhere  on 
the  face  of  the  earth  under  the  most  varied  conditions. 
To  realize  this  fully  we  have  but  to  think  of  the  different 
surroundings  of  the  Eskimo,  Indian,  Bushman,  and  of 
ourselves. 

Each  animal  and  plant  is  directly  dependent  upon  its 
environment  for  food  and  a  home. 

125.  Economic  Value  of  Amphibians.  —  The  toad  is  the 
only  member  of  the  amphibian  group  that  is  of  any  great 
value  to  man.  It  destroys  many  insects.  Frogs  eat  a  few 
but  hardly  enough  to  entitle  them  to  high  rank  as  bene- 
ficial animals.  Their  chief  value  is  as  food  and  as  conven- 
ient forms  for  dissection  in  biology  courses. 

SUMMARY 

The  Amphibians  are  an  interesting  group  which  illus- 
trates how  water  animals  may  have  become  land  animals. 
The  frog  has  well-developed  sense  organs,  legs  modified 
for  jumping,  and  feet  for  swimming.  The  skin  is  moist  and 
helps  to  serve  as  an  organ  of  respiration.  The  color  mark- 
ings and  the  habits  of  the  frog  serve  to  protect  him  from 
many  of  his  enemies. 

QUESTIONS 

What  animals  belong  to  this  class?    How  can  yon  tell  them  from  fish  ? 
Where  do  the  amphibians  of  your  region  live?     Bow  many  kinds  d<> 
you  know  ? 


128  AMPHIBIANS 

See  how  many  kinds  of  amphibian  eggs  you  can  find. 
How  long  do  tadpoles  live  before  they  become  frogs  ? 
What  do  frogs  and  toads  eat? 

What    is    fertilization?      Metamorphosis?      Evolution?      Heredity? 
Environment  ? 

REFERENCES 

Dickerson,  The  Frog  Book. 
Hodge,  Nature  Study  and  Life. 
Holmes,  Biology  of  the  Frog. 
Marshall,  The  Frog. 
Morgan,  Embryology  of  the  Frog. 


CHAPTER   XII 


REPTILES 


Figure   125.  —  A  Sea  Turtle. 


126.  Reptiles.  —  Among  the  Reptiles  (rep'tflz)  are  in- 
cluded lizards,  snakes,  alligators,  turtles,  and  crocodiles. 
The  Reptilia  (Latin, 
repo,  to  crawl)  are  char- 
acterized by  a  covering 
of  bony  plates,  or  scales, 
in  the  skin,  by  the  ab- 
sence of  gills  in  the 
adult  stages,  and  by  the 
presence  of  lungs. 

127.  Life  History.  — Unlike  the  amphibians,  the  reptiles 
hatch  directly  into  their  adult  form,  only  much  smaller. 

The  young  snake  just 
out  of  the  egg  or  the 
young  alligator  just 
hatched  is  recognized 
by  its  resemblance  to 
its  parents. 

There  is  no  meta- 
morphosis, as  in  the 
frog.  The  reptiles  lay 
their  eggs  in  protected 
places  and  exhibit  no 
parental     care    for    the 


Figure  126.  —  Horned  Toad,  a  Lizard. 

Showing  egg-capsules  in  which  the 
young  are  hatched. 


eggs  or  for  the  young.     Some  snakes  hatch  their  young  in 
the  body  of  the  parent  and  the  offspring  are  born  alive. 

i  If  desired,  this  chapter  may  be  omitted  without  affecting  the  sequence  in 

the  book. 

129 


130 


REPTILES 


128.  Turtles. — Turtles  are  easily  recognized  by  their 
outer  skeleton.  This  skeleton  is  unlike  the  skeleton  of 
the  starfish  or  crab,  or  of  any  other  group  of  animals.    The 


Figure   127.  —  Bull  Snake  with  Hen's  Egg  in  Mouth. 

skeleton  of  the  turtle,  composed  mostly  of  skin  plates,  is 
something  like  a  box  with  a  cover,  the  upper  portion  cor- 
responding to  the  box  itself,  and  the  lower  portion  to  the 


Figure  128.  —  Bull  Snake  after  Swallowing  Egg. 

cover.  The  box  does  not  fit  closely  all  the  way  around, 
for  there  are  places  where  the  head,  the  tail,  and  the  four 
legs  stick  out.     When  the  turtle  is  disturbed,  the  legs, 


SNAKES 


131 


the  head,  and   the  tail  are  drawn  inside,  and  the  box   is 
pulled  down  tightly  by  muscles  to  meet  the  cover. 

The  term  turtle  is  often  applied  to  aquatic  forms,  and 
the  term  tortoise  to  those  living  on  land.  Sea  turtles 
attain  a  length  of  six  or 


eight    feet    and    weigh 


Figure  129.  —  Head  of  a  Rattlesnake. 

Dissected  to  show  the  poison  gland,  a, 
and  its  relation  to  the  tooth.  (Duver- 
moy.) 


sometimes  as  much  as  a 
thousand  pounds.  The 
flesh  of  the  green  turtle 
and  of  the  terrapin 
(ter'ra-pin)  is  used  for 
food. 

129.  Lizards.  —  There 
is  a  great  variety  of 
lizards.  A  common 
lizard   is  the   chameleon 

(ka-me'le-un),  which  has  the  power  of  changing  the 
intensity  of  the  color  in  the  skin  by  moving  the  color 
material  nearer  the  outer  surface  or  drawing  it  away. 
The  horned  toad  of  the  Western  United  States  is  a  lizard 
with  scales  of  varying  length  which  give  it  a  horny 
appearance.     Horned  toads,  instead  of  laying  eggs,  have 

the  eggs  hatched  while 
yet  in  the  oviducts  and 
the  young  horned  toads 
are  born  alive.  A  poison- 
ous lizard  is  the  Gila 
(he'la)  monster  that  oc- 
curs in  New  Mexico  and 
Arizona.     It  has  the  poison  glands  in  its  lower  jaw. 

130.  Snakes.  — Snakes  are  legless  vertebrates  with  long, 
cylindrical  bodies  covered  with  scales.  They  move  by 
means  of  the  scales  (scutes)  on  the  under  side  of  the 
body.     Most  snakes  lay  eggs,  but  a  few  bring  forth  living 


Figure  130.  —  Rattles  of  Rattlesnake. 


132  REPTILES 

young.     Since    snakes  eat  insects,  frogs,  mice,  rats,  and 
rabbits,  they  should  be  considered  beneficial. 

Rattlesnakes1  and  copperheads  are  the  most  common 
poisonous  snakes  of  our  country.  Their  jaws  are  provided 
with  fangs  (Figure  129),  by  means  of  which  a  poison 
is  injected  into  their  prey.  Large  snakes  like  the  black 
snake  or  blue  racer    of    the  United  States,  the  boa  con- 


Figure  131.  —  Rattlesnake — -Poisonous. 
Compare  head  with  snake  in  Figure   132. 

strictor  of  South  America,  and  the  python  (pi'thon)  of 
Asia  are  constrictors.  They  are  able  to  wind  their  bodies 
around  their  prey  and  to  crush  it  to  death.  The  most 
deadly  snake  in  the  world  is  the  cobra  (ko'bra)  of  India, 
where  thousands  of  the  natives  die  annually  from  the  bite 
of  this  snake. 

Snakes  swallow  their  food  whole,  and  as  the  teeth  are 
used  merely  for  holding  their  prey,  they  point  backwards. 

1  The  two  most  common  rattlesnakes  are  the  mountain  rattler  and  the 
massasauge  (mas-sa-sa'ge). 


ALLIGATORS   AND  CROCODILES 


133 


Figure  132. —  Garter  Snake  —  Harmless. 

131.  Alligators  and  Crocodiles.  —  Crocodiles  are  found  in 
the  Southern  United  States,  South  America,  Africa,  and 
India.     Alligators   are    found   in  stagnant   pools   in    the 


Figure  133. —  Eight-foot  Florida  Alligator. 


134 


REPTILES 


Southern  States.     Crocodiles  resemble  alligators  but  have 
narrower  mouths. 

132.  Adaptations.  —  Reptiles  are  peculiarly  adapted  to 
their  environment.  Snakes  that  live  in  trees  are  some- 
times the  color  of  leaves  or  bark.  Some  that  are  harmless  are 
colored  much  like  poisonous  snakes.  An  adaptive  feature 
of  the  crocodile  is  a  fold  of  skin  which  shuts  off  the  mouth 


Figure  134.  —  Alligator  Nest. 

from  the  throat  and  prevents  water  from  entering  the 
throat  while  the  crocodile  is  drowning  its  prey.  The  old 
world  chameleons  have  their  feet  modified  for  clasping 
branches.  In  the  case  of  the  turtles,  those  that  live  in 
the  sea  have  paddle-like  feet  for  swimming,  while  those 
that  live  partly  on  land  and  partly  in  the  water  have  toes 
with  webs.  Lizards  are  almost  always  of  about  the  same 
color  as  their  surroundings. 


SUMMARY 


135 


SUMMARY 

The  reptiles  always  use  lungs  for  breathing.  They 
usually  have  scales  or  bony  plates  in  the  skin  and  have 
either  two  pairs  of  appendages  (turtles,  lizards,  alligators, 
crocodiles)  or  none  (snakes).  It  is  important  to  learn  to 
recognize  poisonous  reptiles,  as  their  bite  is  dangerous. 


Figure  135.  —  Poisonous  Lizards  —  The  Gila  Monster. 

LABORATORY   QUESTIONS 

From  models  or  preserved  specimens  the  difference  between  the  harm- 
ful and  harmless  reptiles  should  be  worked  out.  The  living  turtle  can  be 
studied  easily.  Its  special  skeleton  is  an  illustration  of  protective  adapta- 
tion. Notice  how  the  nostrils  of  the  aquatic  turtle  can  be  closed.  How- 
does  this  help  the  turtle  ? 

QUESTIONS 

AVhat  are  the  most  common  snakes  in  your  vicinity?  Are  fchey 
poisonous?  How  can  you  tell?  Where  do  they  live?  What  do  they 
eat?     How  many  kinds  of  turtles  do  you  know?     Where  do  they  live? 


REFERENCES 

Ditmars,  The  Reptile  Book. 
Jordan,  Kellogg  and  Heath,  Animal  Studies. 
Linville  and  Kelly,  General  Zoology. 
Reese,  The  Alligator  and  its  Allies. 


CHAPTER   XIII 


BIRDS 

133.  Birds.  —  Birds  are  the  only  vertebrates  covered  with 
feathers.  Their  front  legs  are  modified  into  wings. 
Among  some  birds,  like  the  penguins  (pen'gwinz)  of  the 
Antarctic  region,  the  wings  are  not  used  for  flying  but  to 
assist  in  swimming.    In  others,  like  the  eagles  and  condors, 

the  expanse  of  the  wings 
is  sufficient  to  enable 
them  to  fly  away  with 
young  lambs  and  large 
fish.  Between  the  small 
wings  of  the  penguin 
and  the  great  expanse  of 
the  wings  of  the  eagle 
and  the  condor  there 
are  many  variations. 
Bird  wings  are  adapted 
to  the  needs  of  their 
owners.  Sailing  birds,  like  the  gulls,  have  long,  slender 
wings,  while  ground  birds,  like  the  partridge  and  pheasant, 
have  short  wings  capable  of  rapid,  short  flights.  Those 
birds  that  make  the  most  use  of  wings  have  them  best 
developed.  An  example  of  underdevelopment,  which  has 
been  increased  by  domestication,  is  seen  in  the  domestic 
fowl,  a  ground  bird,  which  makes  little  use  of  its  flying 
powers,  and  is  incapable  of  sustained  flight. 

The  legs  of  birds  also  have  many  variations.     In  the  case 

136 


Figure  136.  —  Grebe. 


BIRDS 


137 


of  the  eagles,  hawks,  and  owls  there  are  powerful  claws  for 
seizing  and  holding  prey,  while  ducks  and  geese  have 
long  and  webbed  toes,  adapted  to  swimming.  Seed-eating 
birds  have  weak  claws  which  serve  merely  for  perching. 
Chimney  swifts,  that  spend  most  of  their  time  in  flight 
searching  for  food,  have  well  developed  wings,  and  feet 
used  for  clinging.     Study  Figures  139,  140,  149,  155. 


Figure  137.  —  Herring  Gulls. 

The  beaks  of  birds  show  great  variation  and  adaptation 
for  defense  and  food  getting.  Hawks,  owls,  and  eagles 
have  the  upper  jaw  curved  over,  hooked,  and  adapted  for 
tearing  the  food;  herons  and  bitterns  have  the  beak  modi- 
fied into  a  long,  pointed  weapon  of  offense  and  defense  ; 
grosbeaks  (gros'beks)  and  finches  have  a  short,  stout  beak 
for  crushing  seeds  and  other  hard  foods;  while  humming 
birds  have  a  long,  slender  beak  which  in  some  kinds  is 
curved  so  that  they  may  reach  the  bottom  of  certain 
flowers.     Study  Figures  137,  143,  144,  153,  154. 


138 


BIRDS 


The  birds  show  a 
number  of  other  special 
adaptations  which  are  of 
use  to  them.  These  are 
hollow  bones,  a  keeled 
sternum  (breast  bone), 
and  a  high  body  tem- 
perature. 

The  skeleton  of  a  bird 
shows  a  prominent  ridge 
on  the  breast  bone. 
This  is  the  keel  of  the 
sternum,  which  serves 
as  a  place  of  attachment 
for  the  large  wing  mus- 
cles (Figure  139).  The 
lungs  of  the  bird  are 
small,  but  air  tubes 
extend  into    the  bones, 

so  that  the  body  of   the   bird  is   relatively  lighter  than 

that  of  animals  with  solid  bones. 

Birds  lead  an  active  life,  which  means  that  they  use  a 

great  deal  of  energy.     This  energy  comes 

from  the  oxidation  going  on  in  the  body. 

In  birds,  oxidation  is  more  rapid  than  in 

other  vertebrates,  owing  to  the  fact  that 

they  almost   completely  change   the   air 

with  each  breathing  movement  and  thus 

secure  a  greater  supply  of  oxygen.     The 

rapid  oxidation  requires  a  large  supply 

of  food  to  be  digested  and  assimilated 

rapidly  and   it   also   makes   the    normal 

J  Figure  139.  — 

body  temperature  of  birds  higher  than    Skeleton  of  Mal. 
that  of  other  vertebrates.  lard  Duck. 


Figure  138.  —  Adult  Screech  Owl. 


CLASSIFICATION 


139 


Figure   140.  —  Different  Kinds  of 
Birds'  Feet. 


134.    Plumage.  —  The 

feathers   of    birds    show 

great  variety  in  form  and 

color.     In   some    species 

there   are   certain   colors 

which    always    predomi- 
nate on  the  males,  while 

the    females    have    little 

color ;    in    other   species 

it  is  hard  to  distinguish 

between  the  sexes.     The 

brilliantly  colored  males 

are   supposed    to   attract 

the  females  at  the  mating  season,  while  the  dull  colored 

females  are  inconspicuous  and  less  likely  to  be  attacked 

by  enemies  while  hatching  their  eggs,  or  caring  for  their 

young.  We  may  say, 
therefore,  that  they  are 
protectively  colored. 
The  color  of  birds  varies 
during  the  first  two  or 
three  years  of  life. 

135.  Classification.  — 
Birds  are  usually  di- 
vided  into  groups  ac- 
cording to  their  struc- 
ture. The  shape  and 
size  of  the  beak  and  of 
the  feet  and  wings  are 
the  characteristics  most 
used  in  the  general 
classification.  This  is 
illustrated  by  a  single 
Figure   141.  — Loggerhead  Shrike.  group      of      birds,      the 


140 


BIRDS 


Figure  142.  —  Young  of  Red-tailed  Hawk  —  Beneficial. 

hawks,  owls,  and  vultures,  which  are  given  the  technical 
name  of  Raptores  (rap-t5'rez  Latin,  rapere,  to  ravish), 
birds  of  prey.     The  bird  books  describe  the  Raptores  as 


Figure  143.  —  Head  of  Young  Eagle. 


CLASSIFICATION 


141 


follows:  toes  four,  three  in  front  and  one  behind,  except 
in  the  vultures  ;  all  toes  armed  with  strong,  sharp,  curved 
talons  (tfil'iinz);  bill  with  a  cere  (ser  :  Latin,  sera,  wax) 
or  covering  of  skin  at  its  base  through  which  the  nostrils 
open,  very  stout  and  strong,  the  upper  mandible  tipped 
with  a  sharp  pointed  hook. 

In  addition  to  this  classification  by  structure,  which  is 
essential  for  a  careful  study  of  birds,  they  are  also  classi- 
fied by  their  habits.  For  example,  birds  are  divided  into 
four  classes  based  on 
their  migratory  habits. 
Birds  like  the  downy 
woodpecker  and  English 
sparrow  are  permanent 
residents  throughout 
their  range,  that  is,  they 
can  be  found  within 
given  limits  at  any  time 
of  year,  while  bobolinks 
and  humming  birds  are 
summer  residents,  mi- 
grating southward  at 
the   end   of  the   season. 

Birds  like  wild  geese,  fox  sparrows,  and  the  like,  arc 
transients,  stopping  along  their  migratory  route  for  rest 
or  food  or  to  escape  unfavorable  weather;  while  such 
birds  as  the  snowy  owl,  great  northern  shrike,  and  red- 
poll are  winter  visitants  which  have  migrated  to  us  from 
the  North  when  the  cold  became  excessive  and  the  food 
supply  diminished. 

Birds  are  classified  also  by  their  nesting  habits.  Some 
birds,  like  the  meadow  lark  and  bobolink,  nest  in  the  open 
field,  and  their  nests  are  made  inconspicuous  rather  than 
inaccessible;    other  birds,   like  certain  hawks  and  eagles, 


Figure   144.  —  The  Robin. 
Sometimes  a  winter  resident. 


142 


BIRDS 


Figure   145.  —  Nest  of  Goldfinch. 
Nest  of  altricial  bird. 


build  their  nests  in 
tall  trees,  making  them 
conspicuous,  but  inac- 
cessible. Still  others 
build  like  the  oriole 
at  the  end  of  slender 
branches  where  they 
are  out  of  reach  of 
animals.  Birds  like 
the  kingfisher,  sand 
swallow,  and  puffins 
build  their  nests  at  the 
bottom  of  a  burrow  in 
the  ground. 
136.  Nest  Building.  — 

Birds    show   great    variation    in    nest    building.      Some 

build  a  large  nest  with  materials  loosely  put  together; 

others   build   small  nests  of  neatly  woven   material,  and 

some   birds,  like   cowbirds,  build  no  nest  at  all,   but  lay 

their   eggs    in    the   nests   of 

other    birds    and    leave    the 

work     of     caring     for     their 

young  to  the  foster  parents. 
The  number  of  eggs  that 

birds  lay  in  their  nests  varies 

from  one  to  as  many  as  thirty 

or  forty.     The  time  required 

to  hatch  the  eggs  varies  from 

ten  days  to  six  weeks.     Birds 

whose  eggs  hatch  in  ten  days 

or  two  weeks  are  called   al- 
tricial    (al-trl'shal  :      Latin, 

altrix,  nurse),  for  such  young 

are    hatched   helpless,   blind, 


Figure    146. —  Nest  of  Least 
Bittern. 


MIGRATION 


143 


and  with  little  down.  Eggs  that  hatch  in  from  three  to 
six  weeks  develop  well-formed  young,  able  to  run  around 
within  ten  to  twelve  hours  after  hatching.  These  are 
known  as  prcecocial  (pre-ko'shal  :  Latin,  prae,  before; 
coquere,  ripen).  Such  birds  have  little  need  for  a  sub- 
stantial nest  and  few  of  them  build  one.     The  robin  is 


Figure  147.  —  Mourning  Dove. 

altricial,  and  the  domestic  fowl  prsecocial  (Figures  1  |.~> 
and  146). 

137.  Migration.  —  Because  they  are  provided  with  wings 
and  the  power  to  fly  long  distances,  birds  are  able  to  move 
from  one  region  to  another  for  the  purpose  of  finding  food 
and  rearing  young.  The  precise  cause  of  migration  is 
still  unknown.  Birds  in  general  migrate  to  a  warmer 
climate  in  the  fall  of  the  year  and  return  to  the  cooler 
region  in  the  springtime.  In  some  cases  birds  cross  the 
equator  in  migrating.      For  example,  the  bobolink  nests  in 


144 


BIRDS 


the  Northern  United 
States  and  passes  the 
winter  in  South  Amer- 
ica, migrating  a  distance 
of  over  five  thousand 
miles.  In  the  case  of 
the  robin  the  migration 
is  limited  to  a  short 
flight  to  the  south  to 
some  protected  swamp 
provided  with  water  and 
food.  A  probable  cause 
of  migration  is  the  fail- 
ure of  food  supply  as 
cold  weather  comes  on 
in  the  fall. 

138.  Economic  Impor- 
tance of  Birds.  —  The 
chief    food    of   birds   is 

insects,  such  as   plant  lice,  larvae  of  beetles,  butterflies, 

moths,  borers,   etc.     The    chickadee,   for  example,   feeds 

on  plant  lice  as  well  as 

other  foods  ;  the  downy 

woodpecker     feeds     on 

codling       moths       and 

borers  ;   the  nuthatches 

and  brown  creepers  feed 

on     insects   and    insect 

eggs  that  are  hidden  in 

crevices  and  under  loose 

pieces  of  bark.     Other 

useful  birds  are  the  song 

sparrow,  chipping  spar- 


Figure  148.  —  Chimney  Swift  and  Nest. 
Part  of  the  birds  have  been  crowded  out. 


row,     robin,     bluebird, 


Figure  149.  —  Junco. 

A  transient  bird  nesting  in  Canada,  and 
on  the  high  hills  and  mountains  of 
the  Northern  states. 


ECONOMIC  IMPORTANCE 


14.-) 


Figure  150.  —  Female  Bobolink. 


wren,  blackbird,  etc.,  which 
feed  principally  on  insects 
that  are  found  on  or  near 
the  ground.  The  insects 
that  fly,  like  mosquitoes, 
gnats,  and  house  flies,  are 
eaten  by  swifts,  swallows, 
night  hawks,  king  birds, 
and  fly  catchers. 

Among  the  hawks  and 
owls  is  found  a  long  list 
of  beneficial  birds,  for  the 
screech  owl,  red-tailed  hawk, 

and  the  red-shouldered  hawk  are  almost  without  excep- 
tion valuable  as  destroyers  of  shrews,  moles,  mice,  rats, 
weasels,  and  rabbits.  The  hawks  that  are  partly  harmful 
are  the  sharp-shinned  hawk,  Cooper's  hawk,  and  the  marsh 
hawk.     All  of  these  help  themselves  to  poultry  and  feed  on 

small  beneficial  birds 
like  the  song  sparrow 
and  bluebird. 

The  exact  relation  of 
birds  to  agriculture  and 
the  foods  that  they  cat 
has  been  a  subject  of 
study  by  the  Depart- 
ment of  Agriculture. 
Fisher  reports  the  fol- 
lowing' results  in  his 
analysis  of  the  stomach 
contents  of  220  red- 
shouldered  hawks :  ;,»  of 
them  contained  poultry, 
Figure   151.  — King  Bird.  12    of     them     held    102 


146 


BIRDS 


Figure  152.  —  Young  Crows  in  Nest. 


mice,  40  of  them  other  mammals;  20  of  them  reptiles; 
39  of  them  amphibians  ;  92  of  them  insects  ;  and  16  of 
them  spiders.  A  similar  analysis  of  133  stomachs  of 
Cooper's  hawks  shows  the  following  :  34  of  the  stomachs 
contained  poultry  or  game  birds,  52  contained  other  birds ; 

11  of  them  mammals  ; 
1  of  them  a  frog  ;  3  of 
them  lizards,  2  of  them 
insects,  while  39  of  them 
were  empty. 

Aside    from    being    of 

value  in  the  destruction 

of  insects,  birds   destroy 

waste   matter    and    dead 

Figure  153.  —  Kingfisher.  animals      lying      Oil      the 


ECONOMIC  IMPORTANCE 


147 


ground.  The  vultures 
and  buzzards  of  the 
South  and  West  eat 
dead  animals.  The 
gulls  of  the  sea  and 
lakes  destroy  refuse 
thrown  upon  the  sur- 
face of  the  water.  The 
eagle  is  also  a  scavenger 
as  it  eats  dead  fish  that 
float  on  the  surface  of 
the  water,  or  small  dead 
animals  thrown  out  in 
the  open  on  the  land. 
Crows  also  eat  dead 
fish. 

There  is  also  a  group  of  birds  that  lives  largely  on  seed, 
and  such  birds  destroy  vast  amounts  of  weed  seeds. 
Among  the  seed  eaters  are  the  quail,  grouse,  pheasant, 
goldfinch,    sparrows,    bobolink,    and    meadow    lark.       A 


Figure   154.  —  Hairy  Woodpecker 
Eating  Suet. 


Figure  155. —  Male  and  Female  Cowbirds. 


148 


BIRDS 


—  -e- 


• /I?" • 


-,//>-J\y       f-*\    <f-z\ 


—  7Ar"—    —•-<?-- 


Figure  156.  —  Plan  for  Bird  House. 


definite  plan  for  bird  study  is  suggested  in  the  Ap- 
pendix. There  are  many  facts  which  we  should  know 
about  each  bird  which  are  more  important  than  knowing 
its  name. 

One  of  the  best  times  to  study  birds  is  in  the  winter  by 
means  of  feeding  stations  (Figures  154,  155).  If  you  have 
trees  near  your  home,  especially  if  you  live  on  the  edge  of  a 

city  or  in  a  country 
town,  it  is  a  simple 
matter  to  get  birds  to 
come  to  you.  It  will 
take  a  little  time  for  the 
birds  to  learn  that  you 
are  friendly.  The  first 
ones  to  come  will  be 
house  sparrows  and  their 
noisy  chatter  helps  to 
attract  other  birds. 

Each  feeding  station 
may  have  one  kind  of 
food,  as  suet,  seeds,  bread 
crumbs,  or  whole  grain. 
Some  of  the  birds  will 
visit  all  of  the  feeding  places,  but  in  general  birds  are 
either  seed-eating  or  suet-eating. 

At  a  suet  station  one  may  expect  to  see  the  following  : 
Screech  owl,  woodpecker,  blue  jay,  crow,  tree  sparrow, 
junco,  rosebreasted  grosbeak,  myrtle  warbler,  brown 
creeper,  nuthatch,  chickadee.  At  a  hemp  and  millet  seed 
station:  Pine  grosbeak,  red  poll,  goldfinch,  pine  siskin, 
vesper  sparrow,  white-crowned  sparrow,  white-throated 
sparrow,  song  sparrow,  junco,  nuthatch,  chickadee,  purple 
finch.  At  a  bread  crumb  station  :  Blue  jay,  crow,  tree 
sparrow,  brown  creeper.     At  a  station  where  whole  grain 


Figure  157.  —  Plan  for  Bird  House. 


SUMMARY  149 

is  used :  Blue  jay,  crow,  white-breasted  nuthatch,  chickadee, 
quail,  grouse.1 

SUMMARY 

Because  of  their  feathers  birds  can  be  easily  recognized. 
The  fore  limbs  are  adapted  for  flying,  and  as  such  vary  in 
size.  The  feet  are  modified  for  swimming,  running,  perch- 
ing, or  tearing  ;  while  the  jaws  are  large  and  powerful,  or 
small  and  weak,  depending  on  the  habits  of  each  bird. 
The  classification  of  birds  according  to  their  habits  makes 
it  easy  to  learn  about  them.  Birds  are  of  great  economic 
importance  in  destroying  many  kinds  of  insects  that  are 
detrimental  to  man.  This  explains  why  they  must  be 
protected  by  law. 

FIELD   SUGGESTIONS 

The  plan  for  field  study  will  be  found  too  extensive  for  the  time  avail- 
able in  this  course,  but  many  are  anxious  to  continue  studying  birds  for 
several  years,  and  the  plan  in  the  Appendix  suggests  a  systematic  method 
from  the  habit  point  of  view.  Certain  parts  of  this  plan  should  be  under- 
taken whenever  birds  are  taken  up  in  the  course.  Students  will  find  this 
an  interesting  way  to  spend  part  of  the  summer  vacation. 

QUESTIONS 

How  many  birds  do  you  know  ?  What  do  they  eat  ?  Do  they  remain 
all  winter  ?  Which  ones  migrate  ?  Where  do  they  nest  ?  What  time  of 
year  do  the  young  leave  the  nest  ?     Why  are  the  birds  beneficial  ? 

REFERENCES 

W.  L.  McAter,  How  to  Attract  Birds  in  North  Eastern  United  States 
Farmers'  Bulletin  621. 
Chapman,  Bird  Life. 


i  W.  L.  McAter,  How  to  Attract  Birds.    Fanners'  Bulletin  621, 


CHAPTER   XIV 


MAMMALS 


139.  The  Mammals  are  the  most  highly  developed  of  the 
vertebrates.  They  are  warm  blooded  (the  body  tempera- 
ture remaining  the  same  in  winter  and  summer),  breathe 
by  means  of  lungs,  and  are  provided  with  milk  glands  to 
nourish  the  young.  Most  mammals  are  covered  with 
hair.     A  muscular  wall  (diaphragm)  subdivides  the  body 


Figure  158.  —  Skeleton  of 
Dog. 


Figure  159.  —  Coyote. 


cavity  into  parts.  The  upper  part  contains  the  heart  and 
lungs,  and  the  lower  part  contains  the  stomach,  intestines, 
liver,  and  other  organs.  At  birth  the  young  look  like  the 
parents. 

Most  mammals  have  two  pairs  of  limbs.  The  fore  limbs 
may  be  variously  modified  for  different  uses,  as  for  walk- 
ing in  animals  like  the  horse,  for  climbing  and  for  food- 

150 


THE   MAMMALS 


151 


Figure  160.  —  Gray  Squirrel. 


Figure  161.  —  Young  Gray  Squirrel 
LeavIng  its  Nest. 


Figure  162.  —  Young  Foxes. 


Figure  163.  —  Bat  Hibernating. 


152 


MAMMALS 


Figure  164.  —  Brown  Bat. 
Showing  formation  of  wings. 

getting  in  the  squirrel,  for  burrowing  and  locomotion  in 
the  moles,  for  flying  in  the  bats,  and  for  swimming  in  the 

seals.  In  all  fore  limbs 
of  mammals,  even  in 
those  as  different  as  the 
leg  of  the  squirrel,  the 
flipper  of  the  seal,  and 
the  wing  of  the  bat,  the 
arrangement  of  the 
bones  is  the  same.  The 
hind  legs  of  mammals  do 
not  show  so  much  varia- 
tion as  the  fore  limbs. 
But  in  some  cases,  as  in 
the  whale,  the  hind  legs 
have  practically  disap- 
peared through  disuse, 
and  there  is  no  external 
evidence  of  them.  Some 
animals,  like  the  bears, 
walk  on  the  soles  of  their 
Figure  165.  —  Flying  Squirrel.  feet,  and  some,  like  the 


THE  HORSE 


153 


cats  and  the  dogs,  walk  on  all  of  their  toes.  In  some 
mammals  there  is  a  variation  in  the  number  of  the  tots. 
For  example,  the  cow 
walks  on  two  toes  and 
the  horse  on  one  toe, 
the  hoof  being  a  modi- 
fied toe  nail.  In  such 
cases  the  other  toes  are 
entirely  lacking  or  rudi- 
mentary (not  perfectly 
developed). 

140.  The  Horse.— The 
horse  is  interesting  be- 
cause it  has  been  associ- 
ated with  man  since 
the  pre-historic  period 
known  as  the  Stone  Ace. 


Figure   166.  —  Deer  Mouse. 
A  nocturnal  rodent. 

It  has  been  suggested  that  man 


"first  hunted  horses  for  food,  then  drove  them,  and  finally 


Figure  167.  —  Sea  Lions. 


154 


MAMMALS 


Stomach  of  Sheep 


Oesophagus 


-Rumen 


Abomasum 


'Reticulum 


'Intestine 


Figure  168.  —  Stomach  of  Sheep. 

Sheep,  deer,  and  cows  chew  the  "cud" 
and  all  have  stomachs  of  several 
compartments. 


used  them  for  riding  and 
as  beasts  of  burden." 
The  fine  animals  which 
we  see  to-day  have  grad- 
ually developed  through 
this  long  time  from  a 
small  animal  about  the 
size  of  a  fox  terrier. 
The  earliest  remains  of 
the  feet  of  the  ancient 
horse  show  that  it  had 
four  toes  and  the  remains 


of  a  fifth  in  the  front  foot,  while  the  hind  foot  had  three 
toes  and  the  remains  of 
a  fourth.  The  horse  and 
the  deer,  which  also  has 
many  stages  preserved 
in  the  rocks,  afford  ex- 
amples of  the  manner 
in  which  some  of  our 
present  animals  have 
developed.  This  is  an- 
other good  illustration 
of  evolution. 

141.  Economic  Importance  of  Mammals.  —  When  we  con- 
sider the  value  to  man 
of  horses,  cattle,  sheep, 
pigs,  and  goats  in  this 
country,  and  the  value 
of  the  camel  and  rein- 
deer in  other  countries, 
we  can  see  the  great 
economic  importance  of 
Figure  170.  —  Young  Rabbits.  mammals.  Mammals 


Figure  169.  —  Skunk. 


ECONOMIC   IMPORTANCE 


1 .").") 


Report  on  Mammals  to  be  filled  out  first  from  general  knowledge,  later 
extended  by  trips  to  fields,  woods,  or  parks. 


Kinds 


Wheee 
Found 

I'<  >OD 

Kind  of 
Food 

I. Ill        IS 

W'lNTKK 

Life  in 

Si  mm  Kit 

I'.l    M  II'    1  \l 

II  u:\li  ii 


are  useful  as  food,  companions,  beasts  of  burden,  and  for 
clothing.  The  furs  of  wild  animals  and  the  leather  and 
the  wool  of  domestic  animals  are  most  important  in 
protecting  the  body  of  man  from  unfavorable  weather. 
Among  the  domestic 
animals  the  horse  is 
useful  for  driving  and 
draught  work,  and  the 
cow  for  its  flesh,  milk, 
and  butter.  The  sheep, 
through  its  flesh  and 
wool,  is  an  economic 
factor  of  great  impor- 
tance in  civilization. 
There  are  harmful 
mammals  like  gophers 
(go'ferz),  prairie  dogs, 
rabbits,  rats,  and  mice. 
Lions  and  tigers  some- 
times kill  human  be- 
ings. Weasels,  skunks, 
and  mink  are  often 
harmful  in  poultry 
yards. 


Figure   171.  —  Elk. 


156 


MAMMALS 


Figure  172.  —  Virginia  Deer. 


Figure  173. —  Fawns  of  the  Virginia  Deer. 


ECONOMIC  IMPORTANCE 


157 


Figure  174.  —  Coon. 


Figure   175.  —  Young  Woodchucks. 


158 


MAMMALS 


Figure  176.  —  Camel.  The  Ship  of  the  Desert. 
In  making  long  trips  across  the  desert,  the  camel  is  able  to  go  without 
drinking.  During  these  journeys,  the  hump  grows  smaller  as  the  fat  in 
it  is  used  as  food.  This  food  is  gradually  changed  until  part  of  it  be- 
comes water.  We  might  say  that  the  fat  in  the  camel's  hump  is  a 
special  water  reservoir. 


Figure  177.  —  Buffalo. 
These  sturdy  animals  once  roamed  the  plains  in  great  numbers. 
were  not  protected  in  park  preserves,  they  would  now  be  extinct. 


If  they 


SUMMARY  159 

SUMMARY 

The  animals  which  are  called  mammals  are  covered  with 
hair,  and  nourish  their  young  with  milk.  There  are  nearly 
always  two  pairs  of  appendages  that  undergo  much  modi- 
fication according  to  the  habits  of  the  animals.  (  )ur 
domestic  animals  which  serve  us  in  so  many  ways  have  grad- 
ually developed  into  their  present  form  and  usefulness. 
Man  had  to  learn  first  how  to  use  the  fur  and  skin  of  wild 
animals,  then  how  to  improve  the  quality  of  the  fur  and 
skin  by  careful  feeding  and  breeding  of  the  domesticate! 
animals. 

FIELD   SUGGESTIONS 

If  you  are  where  you  can  visit  a  Zoological  park  it  is  an  easy  matter  to 
learn  how  to  distinguish  the  different  nianimals,  a  thing  which  every  one 
should  be  able  to  do.  There  is  another  line  of  study  which  consists  in 
selecting  some  one  or  two  of  the  common  mammals,  such  as  squirrels,  and 
making  a  thorough  study  of  them  from  week  to  week,  month  to  month, 
year  after  year,  until  you  feel  thoroughly  acquainted  with  them.  A  third 
line  of  study  is  that  of  hibernation.  Some  mammals  do  not  hibernate, 
some  do  so  only  during  cold  snaps,  while  others  go  to  sleep  for  the  entire 
winter. 

QUESTIONS 

How  do  you  tell  a  mammal  from  other  vertebrates  ?  What  mammals 
live  near  your  home  ?  What  do  they  eat  ?  Where  do  they  spend  the 
winter  ? 

REFERENCES 

Davenport,  Domestic  Animals  and  Plants. 
Linville  and  Kelly,  Zoology. 
Plumb,  Types  and  Breeds  of  Farm  Animals. 
Stone  and  Crane,  American  Animals. 


PART   II 

HUMAN  BIOLOGY 

CHAPTER    XV 

LIPE  PROCESSES  OF  MAN 

142.  Adaptation.  —  Adaptation  includes  all  the  variations 
in  structures  and  habits  which  have  been  formed  by  an 
animal  or  plant  to  enable  it  to  live  in  its  own  particular 
environment.  Thus  certain  forms  are  adapted  to  living  in 
the  tropics,  others  in  the  temperate  regions,  and  still  others 
in  the  arctic  regions.  Living  things  which  can  adapt  their 
lives  to  our  northern  winters  do  not  need  to  migrate  south 
as  cold  weather  comes  on  in  the  fall.  The  frog  cannot 
migrate,  but  hibernates  in  the  mud. 

Man  is  the  best  adapted  of  all  animals  to  live  in  all  parts 
of  the  world.  When  and  where  man  began  to  live  on  the 
earth  is  not  accurately  known,  but  it  was  many  thousands 
of  years  ago.  He  has  been  able  to  spread  over  the  face  of 
the  earth  because  he  can  control  his  surroundings,  that  is, 
if  he  happens  to  live  where  there  are  many  enemies,  he  in- 
vents destructive  weapons  and  kills  his  enemies  or  drives 
them  away.  This  is  true  even  of  disease,  —  man's  greatest 
enemy.  Again,  most  animals  are  either  flesh-eating  or 
plant-eating,  but  man  is  both,  and  because  he  lias  learned 
to  eat  a  greater  variety  of  both  kinds  of  food  than  any 
other  animal,  it  is  easier  for  him  to  live  and  to  raise  his 
children  in  all  climates. 

161 


162 


LIFE  PROCESSES  OF   MAN 


All  of  the  animals  so  far  studied  have  been  able  to  live 
only  in  their  own  limited  surroundings.  The  grasshopper, 
the  earthworm,  the  paramoecium,  and  the  crayfish  are  not 
found  in  the  sea  or  arctic  regions.  If  the  paramoecium  or 
the  crayfish  is  placed  in  sea  water,  where  the  lobster  and 
many  unicellular  animals  live,  it  dies.  On  the  other 
hand,  if  the  starfish  or  some  of  the  seafish  are  placed  in 
fresh  water,  they  die.  All  of  these  animals  are  adapted 
to  their  own  limited  surroundings. 

Scientists  give  four  reasons  in  explaining  why  animals 
and  plants  are  not  adapted  to  live  in  all  parts  of  the 
world:  (1)  lack  of  suitable  food  ;  (2)  failure  in  adapting 
their  lives  to  the  peculiarities  of  climate  ;  (3)  too  many 
enemies  ;   (4)  inability  to  raise  their  young. 

STUDENT    REPORT 

The  following  table  points  out  some  of  the  common  adaptations 
in  animals.  How  are  they  related  to  the  animal's  success  in  life  ?  Name 
some  other  habits  which  help  to  protect  animals. 


Home 

Protection 

7. 

2, 

'SI 

W 

H 
Z 

o 
z 

H 

c 

(J 

Z 

(—1 

o 
Eh 
w 
J 
w 

S5 

-4 

fa 

Z 

z 

H 

n 

1-1 

o 

> 

M 

W 

l-t 

P 

H 

fc 
H 

■- 

63 
W 

OS 

o 

"4 
z 

03 

w 

o 
o 

H 

Eh 

H 

a 

-sj 

05 

X 

© 

>■ 

_! 

H 

Eh 

Q 

O 

< 

£ 

M 

•A 

< 

© 

K 

W 

< 

< 

W 

< 

* 

fe 

ft 

o 

W 

a 

Earthworm     .... 

Grasshopper   .... 

■ 

English  Sparrow       .     . 

, 

Bog 

YOUTH,   MATURITY,   OLD   AGE 


163 


143.  Youth,  Maturity,  Old  Age. — The  life  of  man  is 
divided  into  three  general  periods,  which  are  youth,  the 
period  of  maturity,  and  the  period  of  old  age.  These  same 
terms  are  given  when  describing  the  life  of  animals  and 
plants. 

Youth  is  the  period  when  living  protoplasm  always 
grows,  if  furnished  with  proper  food.  This  is  the  time 
when  boys  and  girls  grow  taller  and 
heavier  each  year  ;  when  the  tree  grows 
new  leaves  and  the  limbs  become  longer; 
and  when  the  small  puppy  is  turning 
into  a  full  grown  dog.  During  this 
period  of  change  the  boys  and  girls,  the 
tree,  and  the  puppy  are  all  nourished 
by  food  and  this  makes  it  possible  for 
them  to  grow. 

Maturity  is  the  period  when  man 
ceases  to  grow  taller,  although  he  con- 
tinues to  eat  food  as  he  did  during  the 
period  of  youth.  The  living  proto- 
plasm in  his  body  does  not  increase  in 
amount.  The  same  can  be  said  of  the 
tree,  for  it  does  not  grow  taller  ;  and 
the  puppy  of  last  year  has  become  a 
full    grown   dog.      During    this    period 


Figure  178.  —  Ali- 
mentary Canal  of 
Frog. 


Compare  with  Fig- 
ure    179.      In    what 
are  they  alike?     In 
of    maturity,    each    living    organism    is     what  different? 

able  to  repair  its   body  as   fast  as  the 

body  wears  out.      The  period  of   maturity  varies   in   all 

living  things  ;  in  some  butterflies  lasting  but  twenty-four 

hours,  in  man  continuing  for  about  twenty-five  years. 

Old  age  in  man  begins  when    the   bodv  wastes  faster 

than  it  is  repaired,  and  in  the  tree  when  growth  Is  over 

and    decay  begins.     During   this   period  of   old    age    all 

living  things  use  food  as  they  did  in  youth  and  maturity, 


164 


LIFE   PROCESSES  OF  MAN 


but  the  body  wastes  faster  than  it  can  be  repaired  and 
death  is  the  final  result.  Old  age  occurs  at  different 
ages  in  different  individuals  ;  and  the  same  is  true  of 
animals  and  plants. 


STUDENT   REPORT 

Fill  out  the  following  table  and  describe  the  digestive  system  of  the 
animals  studied  thus  far  in  Part  I.  This  will  help  you  to  understand 
better  the  parts  of  the  digestive  system  of  man  and  the  work  that  each 
part  does. 


Paramo3cium 

Hydra 

Earthworm 


Frog 


Man 
Etc. 


One  Cell 

Man  y 
Cells 

No 

Digestive 

Tube 

Digestive 

'iUBE 

No  Well 
Defined 

Digestive 
Glands 

Which 

Ones 

Require 

Food  ? 


144.  Digestive  Organs.  —  The  digestive  organs  of  man 
consist  of  the  same  parts  which  have  already  been  described 
for  the  frog.  Each  region  of  the  digestive  organs  is  more 
perfectly  developed  and  the  biological  principle,  the  di- 
vision of  labor,  readies  its  highest  -development  in  man. 
The  parts  of  the  alimentary  canal  in  man  are  :  the 
mouth,  containing  the  teeth,  tongue,  and  glands ;  the 
throat  or  pharynx;  the  esophagus,  the  stomach,  the  small 
and  the  large  intestine.  The  last  part  of  the  large  in- 
testine is  called  the  rectum.  These  several  parts  form  a 
continuous  tube,  and  each  does  a  particular  work  in  di- 
gestion (Figures  178  and  179). 

The  mouth  is  lined  with  a  soft  membrane,  kept  moist  by 
the  saliva  secreted  by  three  pairs  of  glands,  and  poured 


THE  DIGESTIVE  ORGANS 


if..-) 


tongue 


bladder 


oesophagus 


stomach 


into  the  mouth  in  sufficient 
quantities  to  moisten  the  dry 
food  and  thus  assist  in  swallow- 
ing. The  tongue  is  a  muscular 
organ  and  bears  on  its  upper 
surface  many  small  fleshy  pro- 
jections called  papillae  (pa- 
pil'le  :  Latin  papilla,  bud), 
some  of  which  are  fairly  large 
and  are  arranged  on  the  back 
of  the  tongue  in  the  form  of 
a  V  (Figure  180). 

Our  power  to  taste  sweet, 
sour,  bitter,  and  salt,  which  are 
the  four  fundamental  tastes  in 
man,  is  due  mainly  to  certain 
nerve  cells  located  on  the  larger 

papillae.     The  food  stimuli  received  by  the  special  sensory 
cells  of  the  papilhe  are  carried  to  the  brain  by  the  taste 


lar$e 
intestine 


pancreas 


small 
intestine 


appendix 


Figure   179.  —  Alimentary 
Canal  of  Man. 


I 
I  l 


Figure  180.  —  Tongue. 


Figure  181. — Taste  Cells. 

The  taste  nerve  ends  among 
these  cells. 


166 


LIFE   PROCESSES  OF   MAN 


nerves.     In  the  brain  the  food  stimulus  is  interpreted  as 
sweet,  sour,  or  bitter  (Figure  181). 


LABORATORY   STUDY 

Blindfold  in  turn  several  members  of  the  class  and  have  each  hold  his 
nose  while  a  small  amount  of  some  highly  flavored  food  is  placed  on  the 
tongue.  Such  common  foods  as  maple  syrup,  vanilla  extract,  marmalade, 
jams,  etc.,  are  admirable  for  this  test.  Make  a  record  of  each  test.  This 
experiment  will  prove  that  we  do  not  taste  flavors.  Remove  the  hand  from 
the  nose  and  again  taste  the  same  substances.  This  time  there  will  be  no 
difficulty  in  telling  the  name  of  the  substance  because  it  has  been  smelled 
as  well  as  tasted. 

The  roof  of  the  mouth  is  called  the  palate.  The  front 
part  contains  supporting  plates  of  bone  and  is  therefore 
called  the  hard  palate.  The  back  part  (the  soft  palate)  is 
a  thin  sheet  of  muscle  covered  by  the  mucous  lining  of  the 
mouth.  The  palate  separates  the  mouth  from  the  nasal 
cavity.  Beyond  the  soft  palate  is  the  throat  cavity  called 
the  pharynx.  This  is  a  funnel  shaped  cavity,  having 
two  openings  at  its  lower  end,  the  front  one  being 
the  opening  into  the  windpipe  which  leads  to  the  lungs, 
and  the  rear  one,  the  opening  into  the  esophagus.      In 

the  upper  part  of  the 
pharnyx  on  each  side,  is 
the  opening  of  an  eusta- 
chian (u-sta/ki-an)  tube 
which  passes  to  the 
middle  ear. 

Teeth.  —  Just  back  of 
the  lips  are  the  teeth. 
In  adults  there  are 
thirty-two,  sixteen  in 
each  jaw,  belonging  to 
four  classes  according  to  shape.  In  front  are  the  eight 
incisors  (in-si'zers)  with  sharp  cutting  edges  ;    next  the 


Figure  182.  —  Milk  Teeth. 

Age  2>\   to  4  years.     Notice  the  per- 
manent teeth  deeper  in  the  jaws. 


THE    DIGESTIVE   Olid  ASS 


16! 


four  sharp-pointed  canines  (ka/nins),  aiid  back  of  the 
canines   the    eight   pre-molars    (pre-mo'lers)    Bhaped    for 

tearing  and  crushing,  while  the  remainder  of  the  teeth, 
twelve  in  number,  are  the  flat-topped  molars  which  do 
most  of  the  grinding  of  the  food. 

Care  of  the  teeth.  —  We  all  know  that  the  teeth  are 
hard.  That,  however,  does  not  prevent  them  from  becom- 
ing broken  by  carelessness  or  accident,  or  from  decaying 
because  of  neglect.  When  the  teeth  are  not  cleaned,  a 
substance  called  tartar  forms  on  them,  which  prevents 
the  bacteria  from  being  rubbed  off  and  sometimes  pushes 
the  gums  away  from  the 
teeth.  The  bacteria 
cause  food  particles  to 
ferment  and  form  acids 
which  dissolve  the 
hard  outside  covering 
(enamel)  and  then 
rapidly  the  softer  parts 
of  the  teeth.  This  re- 
sults in  toothache,  a 
foul  breath,  and  the  im- 
perfect chewing  of  the  food.  The  teeth  should  be  brushed 
after  each  meal  to  remove  particles  of  food  and  particu- 
larly sugar  which  ferments  easily.  At  least  once  a  year 
there  should  be  a  visit  to  the  dentist  who  will  remove 
those  portions  of  teeth  that  are  decayed  and  will  lill 
cavities,  thus  preventing  further  decay  of  the  teeth.  The 
value  of  good  teeth  cannot  be  overestimated. 

The  esophagus  is  a  nearly  straight  tube  connecting  the 
mouth  with  the  stomach.  It  passes  through  the  diaphragm 
(Figure  208),  enlarges,  and  becomes  the  stomach.  As 
soon  as  one  swallows,  control  of  the  food  is  lost, 
and   further   action  becomes  involuntary.       Two    sets  of 


Figure  183.  —  Permanent  Teeth. 


His 


LIFE   PROCESSES  OF  MAN 


Figure  184.  —  Pear- 
shaped  Human 
Stomach. 


muscles,    one    extending   lengthwise,    the    other    around 

the  esophagus,  act  together  in  forcing  the  food  or  water 

into  the  stomach.  This  explains  why  we 
can  drink  from  a  brook  when  the  head  is 
much  lower  than  the  stomach. 

Stomach.  —  In  man  the  stomach  is  the 
largest  section  of  the  digestive  tube,  and 
it  has  a  capacity  of  about  three  pints. 
It  is  usually  described  as  pear-shaped 
although  there  is  much  variation  in  its 

form  (Figures  184  and  185).     At  the    point    where    the 

esophagus   joins   the  stomach   there   is  a  muscular  ring 

(cardiac  valve,  kiir'di-ak)  which  ordinarily  prevents  the 

food  from  passing  again  into  the  esopha- 
gus.    In  vomiting,  this  valve  becomes 

relaxed.      The   opening   at   the   larger 

and  lower  end  of  the  stomach  is  guarded 

by  a  similar  valve   (pyloric,  23i-16Vik) 

which  serves  to  retain  the  food  in  the 

stomach  until  certain  digestive  changes 

have  taken  place. 

The  intestine  has  two  parts,  a  small, 

much    coiled    tube    about    an    inch    in 

diameter  and   about  twenty   feet   long 

called  the  small  intestine;    and  a  large 

section   about  five  feet  long  and   four 

inches    in   diameter,   bent   in   a   rough 

p   shape  and  called  the  large  intestine. 

At    the    junction    between    these    two     miliar  to  physicians 

regions  projects  a  short  sac,  the  vermi-     and  is  called  the  J_ 
■p  y       s   ~-  i'   «  j.*  „    ,       shape.  —  Dr.    C.    F. 

jorm    appendix    (vermi-form    ap-peiv-     potter. 

diks).     The  disease  called  appendicitis 
(ap-pend-i-si'tis)    affects   this    organ.      The   large    intes- 
tine ends   in   a  special   region   called   the  rectum.      The 


Figure  185.  —  X-ray 
Photograph  of 
Human  Stomach. 


FOOD 


im 


Figure  186.  —  X-ray  Photo- 
graph of  Appendix  and 
Part  of  Large  Intestine. 

The  constrictions  are  natural. 


opening    of   the   rectum   to   the 

outside  is  the  anus  (a/ntts). 
Glands.  —  A  gland  is  a  group 

of  special  cells  which  secrete  a 

fluid.     The    glands   which   pro- 
duce   the    digestive    fluids    are 

(1)  the  three  pairs  of  salivary 

(sal'i-va-ry)      glands,      located 

below  the  ear,  and  beneath  the 

tongue  and  lower  jaw ;   (2)  the 

numerous      gastric      (gaVtrik) 

glands   found  in  the    lining   of 

the  stomach,  possibly  5,000,000 

in    number  (Figure   187)  ;    (3) 

the  pancreas;  and  (4)  the  liver, 

the  largest  gland  in  the  body. 

145.   Food.  —  One  of  the  best  definitions  of  food  is  the 

following.      Food  is  that  which  when  taken  into  the  body 

builds  up  tissue  or  yields  energy.      All  organic  foods  or 

foodstuffs  are  divided  into  three  classes, 
the  proteins  (pro'te-ins),  the  cdrhoh yd 'rates 
(kar-bo-hi'drats),  and  the /ate.  This  classi- 
fication is  made  whether  we  studv  the 
foods  of  a  plant,  an  animal,  or  of  man. 
Scientists  are  able  to  tell  to  which  class 
meat,  bread,  oatmeal,  milk,  and  all  other 
foods  belong  by  finding  out  the  chemical 
composition  of  each.  The  chemists  have 
made  a  thorough  study  of  food  and  tell 
us  that  certain  chemicals  are  present  in 
each  of  the  three  classes  of  foods.  Defi- 
nite chemical  tests  tell  us  to  which  of 
these  three  classes  any  given  article  of  food 

Figure  187.  —  \   °  .       _  . 

Gastric  Gland     belongs.     In  general  it  may  be  said  that  the 


170 


LIFE  PROCESSES  OF  MAN 


proteins  are  necessary  for  the  growth  and  the  repair  of  the 
bodv,  and  that  the  carbohydrates  and  fats  furnish  heat  to 
keep  the  body  warm,  and  energy  for  muscular  work.  The 
unused  fat  is  stored  up  as  fatty  tissue.  All  classes  of 
food  are  found  in  the  various  foods  obtained  from  plants. 
Some,  like  honey,  are  nearly  pure  carbohydrate,  while  the 
English  walnut  contains,  in  addition  to  fat,  a  large  quantity 


£t^3^'"«~^-  v3"'^r*0 


> 


;-=?cj 


* 


Figure  188.  —  Microphotograph  of  Stomach. 

The  stomach  is  an  organ  composed  of  several  tissues  arranged  in 
layers.  The  gastric  glands  are  in  the  innermost  ragged  layer  and 
look  like  rows  of  black  dots. 


of  plant  protein.  Animal  foods  can  furnish  us  with  only 
proteins  and  fats.  In  primitive  times  man  used  a  re- 
stricted diet  and  led  an  active  out-of-door  life.  To-day 
man  is  living  on  a  mixed  and  varied  diet.  This  is  to  be 
regarded  as  an  acquired  habit  and  one  that  is  questionable 
when  carried  to  an  extreme.  The  question  of  how  much 
to  eat  is  a  modern  problem,  and  on  its  solution  depend  our 
health,  length  of  life,  and  energy  for  work. 


Thomas  Henry  Huxley  (1825-1895)  was  a  celebrated  English 
biologist.  As  a  young  man  he  made  a  trip  around  the  world  in 
H.M.S.  Rattlesnake,  which  was  on  surveying  service  in  Australasia. 
On  reluming  home  Huxley  devoted  himself  to  the  study  of  biol- 
ogy. He  held  a  number  of  important  academic  positions  and 
was  made  President  of  the  Royal  Society  in  1883. 

Huxley  was  one  of  the  most  laborious  workers  in  biology.  He 
rearranged  the  animals  in  new  classes  and  discovered  remarkable 
similarities  in  their  development.  He  is  celebrated  for  his  theory 
of  protoplasm  and  for  his  able  advocacy  of  the  views  of  Darwin. 

Huxley  showed  great  skill  in  putting  the  conclusions  of  science 
into  simple  language. 


DIGESTION 


171 


STUDENT   REPORT 

Animals  eat  a  large  variety  of  things,  parts  of  which  serve  to  furnish 
energy  or  to  nourish  the  body.  In  the  following  report,  work  out  the 
sources  from  which  the  animals  derive  their  food.  To  what  extent  ;ue 
they  alike  ? 


Para- 
mecium 

HVDUA 

Earth- 
worm 

Frog 

Man 

Flies 

Minute  plants    .     . 

Minute  animals 

Flies 

Add  food  of  man    . 

146.  Digestion.  —  Digestion  begins  in  the  mouth.  The 
teeth  break  up  the  food  and  mix  it  with  the  fluid  of  the 
mouth,  the  saliva.  During  this  process,  sugars  and 
starches  are  changed  into  soluble  sugars.  The  fluids  of 
the  mouth  are  usually  slightly  alkaline  (al'ka-lm  or  lin, 
a  chemical  term,  the  opposite  to  sour  or  acid),  but  as  soon 
as  the  food  passes  into  the  stomach  it  enters  an  acid  (sour) 
medium,  and  the  digestive  action  of  the  saliva  is  destroyed 
in  a  short  time  by  the  stomach  fluid.  For  this  reason,  the 
sugar  and  starch  undergo  no  further  digestive  changes 
until  they  reach  the  intestines. 

Into  this  acid  medium  of  the  stomach,  the  gastric  glands 
(Figure  179)  pour  out  the  gastric  juice  (a  digestive  fluid), 
and  the  pepsin  in  this  juice  acts  on  the  proteins  so  that 
they  can  later  pass  through  the  walls  of  the  intestines.  In 
the  stomach  the  heat  of  the  body  dissolves  some  of  the  fats 
into  oils,  but  many  of  the  fats  used  as  food  remain  solid 
at  body  temperature  and  are  unchanged  in  1  lie  stomach. 

After  one  or  two  hours  the  food  passes  into  the  intes- 
tine and  undergoes  further  changes  in  another  alkaline 
medium.     Here  the  pancreatic  juice,  which  is  made  in  the 


172 


LIFE   PROCESSES  OF  MAN 


pancreas,  comes  into  contact  with  the  digested  and  partly 
digested  food,  causing  three  different  changes.  One  is  to 
complete  the  change  of  proteins  into  simpler  products ;  a 
second  is  to  finish  converting  starches  into  sugar ;  while 
the  third  is  to  assist  the  bile  (the  digestive  juice  made  in 
the  liver)  to  digest  the  fats.  The  digestion  of  the  food  is 
practically  completed  in  these  three  regions  of  the  diges- 
tive tube,  although  digestion  continues  to  some  extent 
after  the  food  is  passed  into  the  large  intestine. 

The  pepsin  in  the  gastric  juice  is  called  an  enzyme 
(C'li'zim:  Greek  enzymos,  fermented)  or  ferment.  There 
are  three  different  enzymes  in  the  pancreatic  juice,  none 
in  the  bile,  and  one  in  the  saliva.  These  enzymes  are  the 
chemical  bodies  which  digest  food.  All  plants  and  animals 
digest  their  food  by  means  of  enzymes. 

Inorganic  foods,  such  as  water,  oxygen,  and  salts,  man 
takes  into  his  body,  making  them  part  of  his  living  pro- 
toplasm, or  using  them  in  oxidation.  There  is  a  large 
amount  of  water  in  man,  enough  to  make  up  nearly  two- 
thirds  the  total  weight  of  his  body.  AH  of  his  food  con- 
tains water. 
/ 

STUDENT   REPORT 
Where  the  Food  is  Digested 


In  the 
Cell 

In  the 
Leaf 

Primitive 

Digestive 

Tube 

Stomach 

Mouth 

Digested 

by 
Enzymes 

Paramecium     . 

Hydra      .     .     . 

Frog     .... 

Man,  etc.       .     . 

Bean    .... 

Yeast  .... 

Teacher  may  explain  yeast  and  bean  to  help  out  the  comparison. 


ABSORPTION   OF   FOOD  L73 

Oxygen  is  breathed  in  from  the  air,  and  the  various  Baits, 
such  as  common  salt,  sodium  chloride  (so'di-um  kld'rid,  or 
rid),  calcium  (kal'si-um),  magnesium  (lnag-nf-'/.hi-um,  or 
-shi-),jP0ta$8iM??i(po-tas'si-um),  and  phosphorus  (fos'fBr-US  ) 
are  taken  in  with  our  food.  They  are  useful  to  the  body. 
A  small  amount  of  iron  is  also  contained  in  food  and  water 
and  becomes  a  part  of  the  red  blood  cells. 

LABORATORY   STUDY 

Study  food  and  food  tests.  Artificial  gastric  juice  is  easily  prepared 
"by  taking  |  gram  of  pepsin,  Taff  cc.  of  strong  hydrochloric  (hi-drft-klo'- 
rik)  acid  and  adding  50  cc.  of  water.  Take  white  of  egg  that  has  been 
cooked  and  subject  it,  in  a  test  tube,  to  the  above  mixture.  A  variety  of 
tests  should  be  made,  with  and  without  heat  (100  F.)  with  and  without 
the  acid.  Pancreatic  juice  is  made  by  uniting  15  grains  sodium  (so'dl-fim) 
carbonate  (kar'bon-at),  5  grams  pancreatin  (pan'kiv-a-tin),  and  100  cc. 
water.  The  action  of  this  fluid  may  be  tested  as  above  on  the  fata,  as 
■olive  oil ;  on  starch,  as  flour  ;  and  on  proteins,  as  raw  lean  meat  or  milk. 
Also  examine  several  of  the  common  articles  of  food  to  determine  to  what 
•class  of  foodstuffs  they  belong. 

147.  Absorption  of  Food.  —  The  absorption  of  food  in  man 
.and  animals  is  the  process  of  taking  the  digested  foods 
from  the  alimentary  canal  into  the  blood.  Practically  no 
food  is  absorbed  in  the  mouth  or  esophagus,  and  but  little 
in  the  stomach. 

The  absorption  of  food  from  the  intestinal  canal  is 
done  by  small  folds  in  the  lining  of  the  small  intestine. 
To  the  naked  eye,  these  folds  appear  as  a  covering  of 
minute  hairs,  called  villi  (villi).  Their  structure  is  shown 
in  Figure  189. 

The  process  of  osmosis,  which  has  been  so  frequently 
referred  to  in  Part  I,  is  the  chief  factor  in  the  passing  of 
the  food  into  the  blood  vessels.  This  process  is  assisted  by 
the  action  of  the  livinsr  cells  in  a  manner  not  well  under- 
stood. 


174 


LIFE   PROCESSES  OF  MAN 


The  digested  proteins  and  sugars  pass  directly  into  blood 
vessels  which  lead  to  the  liver.  In  the  liver,  these  blood 
vessels  unite  to  form  the  portal  (por'tal)  vein,  which  is 
divided  into  minute  branches  that  distribute  the  blood  to 
the  cells  of  the  liver.  As  the  blood  thus  passes  among  the 
liver  cells,  the  larger  part  of  the  sugar  is  changed  into 
glycogen  (gli'ko-jen),  an  animal  starch,  and  stored  tempo- 
rarily in  the  liver  cells.     This  stored-up  starch  is  given 

out  gradually  and   changed 


urn 


/esse! 


lph  or 


vessels 


Wall 
\of 

Irtres+ine 


back  into  sugar,  which  re- 
sults in  keeping  a  uniform 
amount  of  sugar  in  the 
blood. 

The  fats  pass  into  certain 
distinct  vessels,  lacteah  (lak'- 
te-als),  which  in  turn   open 
into   larger   ones.      Eventu- 
ally  these   vessels   unite   to 
form     a     large     duct  —  the 
thoracic  —  which  empties  into 
one    of    the    veins   near  the 
heart.     The  food  is  now  in 
the     blood     stream    and     is 
carried     to     the     individual 
cells    of    the    body.       Each 
cell  takes  the  kind  of  food  which  it  needs  and  bv  a  series 
of  changes,  as  yet  only  partly   known,  makes   the   food 
into  living  protoplasm. 

The  indigestible  part  of  the  food  is  not  absorbed,  but 
continues  to  move  through  the  small  intestine  into  the 
large  intestine,  and  on  through  the  rectum.  During  this 
progress  much  moisture  is  absorbed,  especially  in  the  large 
intestine,  which  leaves  the  "  undissolved  food "  harder 
and  harder.     The  regular  removal  of  the  unused  part  of 


Figure  189.  —  Diagram  of  Villus. 


ABSORPTION   OF   FOOD 


L75 


the  food,  faeces  (fe'sez),  is  of  much  importance  in  main- 
taining health,  because  the  bacteria  living  in  the  digestive 
tract  cause  the  waste  material  to  decay  and  fche  poisonous 
substances  thus  formed  are  injurious  when  absorbed  into 
the  blood. 

Foods  normally  remain  in  the  stomach  from  one  to  five 
hours,  and  in  the  small  intestine  about  four  hours;   while 
they  may  be  from  six  to 
twenty-four     hours     in 
passing      through      the 
large  intestine. 

We  become  hungry 
each  day  and  feel  re- 
lieved only  after  eating. 
A  person  frequently  eats 
a  large  meal  because  of 
an  extra  amount  of  work 
that  is  to  follow.  But 
is  he  helped  to  do  the 
extra  work  ?  Probably 
not,  for  the  strength  to 
do  the  work  of  to-day 

comes  from  the  food  eaten  yesterday,  or  possibly  the  day 
before  yesterday.  The  food,  even  after  digestion  is  com- 
pleted, must  pass  through  many  changes  before  it  is  built 
up  into  protoplasm.  The  actual  building  of  the  food  into 
protoplasm  is  the  process  for  which  the  word  nourishment 
is  used,  and  it  should  not  be  confused  with  absorption. 

Water. 


Figure  190.  —  Home-made  Apparatus 
to  show  Osmosis. 


Food  as 
purchased 
contains 


Edible  portion 

e.g.,  flesh  of  meat,  yolk  and 
white  of  eggs,  wheat,  flour,  etc 


Nutrients 


Protein. 

Fata 

( Sarbohydrafe  9. 

Mineral  mat; 


Refuse 
e.g.,  bones,  entrails,  shells,  brain,  etc. 


176  LIFE  PROCESSES  OF  MAN 

Alcohol  is  made  up  of  carbon,  hydrogen,  and  oxygen. 
All  proteids  contain  nitrogen  in  addition  to  these  three. 
Because  alcohol  contains  no  nitrogen,  it  cannot  be  used  as 
a  food  to  build  up  tissue. 


All  serve  as 
fuel  to  yield 
energy  in  the 
form  of  heat 
and  muscular 
power. 


USES   OF   NUTRIENTS   IN  THE   BODY 

Protein  Forms  tissue 

e.g.,  white  (albumen)  of  eggs, 

curd,  casein  (ka'se-m)  of  milk,  lean 

meat,  gluten  of  wheat,  etc. 
Fats  Are  stored  as  fat 

e.g.,  fat  of  meat,  butter,  olive 

oil,  oils  of  corn  and  wheat,  etc. 
Carbohydrates  Are  transformed  into  fat 

e.g.,  sugar,  starch,  etc. 
Mineral  matter  (ash)  Shares  in    forming   boner 

e.g.,  phosphates  of  lime,  assists  in  digestion,  etc. 

potash,  soda,  etc. 

Comparative  amount  of  food  required  for  persons  of 
various  ages  and  conditions,  taking  as  the  unit,  the  amount 
of  food  required  by  a  man  at  moderately  active  muscular 
work : 

Man  at  hard  muscular  work  requires  1.2  the  amount  of  food  of  a  man 
at  moderately  active  muscular  work. 

Man  with  light  muscular  work  or  boy  15-16  years  old  requires  0.9. 

Man  at  sedentary  occupation,  woman  at  moderately  active  work,  boy 
13-15,  or  girl  15-16  years  old  requires  0.8. 

Woman  at  light  work,  boy  12,  or  girl  13-14  years  old  requires  0.7. 

Boy  10-11  or  girl  10-12  years  old  requires  0.6. 

Child  6-9  years  requires  0.5. 

Child  2-5  years  old  requires  0.4. 

Child  under  2  years  old  requires  0.3. 

Heat  is  a  form  of  energy  and  one  of  the  reasons  for 
taking  food  is  to  keep  up  the  supply  of  this  energy. 
The  more  work  a  person  does  the  more  energy  he  uses, 
but  even  a  resting  body  uses  some  energy,  'for  the  heart 
beats  and  the  muscles  of  the  chest  move.     The  amount  of 


PREPARATION  OF   FOOD  177 

this  form  of  energy  a  person  uses  is  measured  by  a  unit 
of  heat  named  the  calorie  (kal'6-ri).  A  calorie  represents 
the  amount  of  heat  required  to  raise  the  temperature  of 
a  pint  of  water  about  four  degrees  Fahrenheit.  A  man 
in  rising  from  a  chair,  walking  eight  feet,  and  returning 
uses  about  one  calorie. 

Pecuniary  Value  of  Food.  — The  table  on  page  178  from 
the  government  bulletin  helps  to  give  students  an  appre- 
ciation of  the  relative  cost  and  value  of  the  more  common 
foods. 

148.  The  Preparation  of  Foods.  —  Some  foods,  such  as 
milk,  fruit,  and  nuts,  may  be  eaten  without  being  cooked. 
but  most  of  our  food  has  to  undergo  this  process  before  it 
is  suitable  for  eating.  As  no  two  kinds  of  vegetables  or 
meat  are  best  cooked  in  exactly  the  same  way,  attention 
should  be  given  to  the  preparation  of  food  for  the  table. 
Successful  cooking  accomplishes  four  ends.  (1)  Changes 
are  brought  about  to  make  the  food  more  digestible,  such 
as  softening  or  dissolving  it.  (2)  The  nutritious  parts 
are  carefully  saved.  (3)  Certain  amounts  of  the  three 
classes  of  foodstuffs  are  selected  in  order  that  all  the 
chemical  elements  which  the  body  needs  may  be  supplied. 
This  is  known  as  a  "balanced  ration."  (4)  The  food 
is  made  attractive  in  appearance  and  taste,  "good  to 
eat." 

Every  woman  who  wishes  to  have  a  happy,  healthy 
family  should  make  a  serious  study  of  cooking.  Many  of 
the  facts  about  the  nutritive  elements  which  foods  contain, 
and  the  many  changes  which  they  undergo  in  cooking 
are  found  out  by  chemists  who  study  them  in  laboratories. 
It  is  not  necessary  for  all  of  us  to  know  all  these  facts. 
but  a  good  cook  follows  the  rules  and  recipes  which  have 
been  made  as  a  result  of  scientific  laboratory  studies. 

To  illustrate  how  much  is  involved  in  cooking,  let  us 


178 


LIFE  PROCESSES  OF   MAN 


Comparative  Cost  of  Digestible  Nutrients  and  Energy  in  Dif- 
ferent Fooi>  Materials  at  Average  Prices1 

It  is  estimated  thai  a  man  at  light  to  moderate  muscular  work  requires  about  0.23  pound  oi 

protein  and  3,050  calories  of  energy  per  day. 


a 
y. 

p 
o 
Ph 

C4 

Amounts  for  10  Cents 

KlM>  OF   Material 

©   s 

Weight 

i)  Ma- 

z 

■n 

S 

> 

H      P 

—    z 

\  \ 

z    ~ 
Z    < 

Total 
of  Foe 

TERIAL 

H 
O 

< 

C     < 
<     > 

w         — 

o 

M 
W 

r,  nts 

Dollars 

Cents 

Pou  nds 

Pounds 

Powids 

Pounds 

Calories 

25 

1.60 

25 

0.40 

0.06 

0.06 

— 

410 

1(5 

.87 

18 

.63 

.11 

.08 

— 

:.oo 

Beef,  shoulder  clod      .     .     . 

12 

.  i.» 

17 

.83 

.13 

.OS 

— 

595 

Beef,  stew  meat 

5 

.35 

7 

2 

.29 

.23 

— 

1,530 

Beef,  dried,  chipped    .     .    . 

25 

.98 

32 

.40 

.10 

.03 

— 

315 

Mutton  chops,  l<»iii  .... 

16 

1.22 

11 

.03 

.08 

.17 

— 

890 

20 

1.37 

22 

.50 

.07 

.07 

— 

445 

12 

.92 

10 

.S3 

.11 

.19 

— 

1,035 

Pork,  Bmoked  ham      .     .     . 

22 

1.60 

13 

.45 

.06 

.14 

— 

735 

12 

6.67 

3 

.S3 

.02 

.OS 

— 

2,950 

<  lodfish,  dressed,  fresh     .     . 

10 

.93 

46 

1 

.11 

— 

— 

220 

Halibut,  fresh 

18 

1.22 

38 

.56 

.08 

.02 

— 

265 

i 

.45 

22 

1.43 

.22 

.01 

— 

465 

Mackerel,  salt,  dressed     .     . 

10 

.74 

9 

1 

.13 

.20 

— 

1,135 

Salmon,  canned 

12 

.57 

13 

.83 

.IS 

.10 

— 

760 

( >\  sters,  35 1  per  qt.     .     .     . 

18 

3.10 

80 

.56 

.03 

.01 

.02 

125 

Lobster,  canned 

IS 

1.02 

46 

.56 

.10 

.01 

— 

225 

30 

30.00 

9 

.33 

— 

.27 

— ■ 

1,125 

Eggs,  86^  per  doz 

24 
16 

2.09 
.64 

39 

8 

.42 
.63 

.05 
.16 

.04 
.20 

.02 

260 
1,185 

Milk.  T  c  per  <(t 

3A 

1.09 

11 

2.S5 

.09 

.11 

.14 

s>5 

3 

.31 

••> 

3.33 

.32 

.03 

2.45 

5,440 

Corn  meal,  granular     .     . 

•-'A 

.32 

2 

4 

.31 

.07 

2.96 

6,540 

Wheat  breakfast  food  .     .     . 

T§ 

.73 

4 

1.33 

.13 

.02 

.9S 

2,235 

<  >at  breakfast  food  .... 

>i 

.53 

4 

1  33 

.19 

.09 

.86 

2,395 

4 

.29 

2 

2.50 

.34 

.16 

1.66 

4,500 

8 

1.18 

5 

1.25 

.08 

.97 

2,025 

Wheal  bread 

5 

.04 

4 

2 

.16 

.02 

1.04 

2,400 

5 

.65 

4 

2 

.15 

.01 

1.04 

2,340 

Beans,  white  dried      .     .     . 

5 

.29 

3 

2 

.35 

.03 

1.16 

3,040 

2* 

2.0S 

22 

4 

.05 

.01 

.IS 

460 

6.65 

77 

2 

.02 

— 

.05 

130 

10 

4.21 

23 

1 

.02 

.01 

.18 

430 

Potatoes,  60  p  per  bu.  .     .    . 

1 

.67 

3 

10 

.15 

.01 

1.40 

2,950 

1 

1.33 

8 

10 

.08 

.01 

.54 

1,200 

U 

5  00 

8 

6.67 

.02 

.02 

.65 

1,270 

T 

10.00 

27 

1.43 

01 

.01 

.IS 

370 

6 

12.00 

4ti 

1.67 

.01 

— 

.13 

250 

7 

8.75 

47 

1.43 

.01 

.01 

.09 

215 

G 

— 

3 

1.07 

— 

— 

1.67 

2,920 

1  Principles  of  Nutrition  and  Nutritive  Value  of  Food,  W.  C.  Atwater,  Farmers'  Bulletin 
No.  1  I-.'. 

*The  cost  of  1  pound  of  protein  means  the  cost  of  enough  of  the  given  material  to  furnish 
1  pound  of  protein,  without  regard  to  the  amounts  of  the  other  nutrients  present.  Like- 
wi-e  the  cost  of  energy  means  the  cost  of  enough  material  to  furnish  1,000  calories,  without 
reference  to  the  kind>  and  proportions  of  nutrients  in  which  the  energy  is  supplied.  These 
estimates  of  t  he  cost  of  protein  and  energy  are  thus  incorrect  in  that  neither  gives  credit  for 
the  value  of  the  other. 


PREPARATION  OF   FOOD  179 

see  what  it  means  to  produce  a  loaf  of  wholesome  bread. 
Flour  contains  much    starch,  some  sugar,  some    mineral 

substances  known  as  phosphates,  a  large  quantity  of 
gluten  (a  protein),  and  some  bacteria  (tiny  plant-,  see 
Chapter  XXIV)  which  may  or  may  not  be  of  value  in 
making  bread.  When  water  is  added  to  the  flour,  it 
becomes  tough  and  sticky,  this  being  a  characteristic 
of  gluten,  and  the  most  important  one,  so  far  as  tin- 
making  of  bread  is  concerned.  A  small  bit  of  yeast  (a 
small  plant,  see  Chapter  XXIV)  is  added  to  the  water 
used  in  making  bread,  and  the  dough  is  placed  where  it 
will  be  neither  too  hot  nor  too  cold   (70°-80°  F.). 

The  yeast  begins  to  grow  rapidly,  feeding  on  the 
proteins  of  the  flour,  and  as  the  yeast  grows,  it  acts  od 
the  sugar.  A  substance  called  zymase  (zim'as),  secret ed 
by  the  yeast  plant,  breaks  the  sugar  up  into  carbon 
dioxide,  alcohol,  and  a  small  quantity  of  glycerin.  The 
gas  tries  to  escape,  but  is  held  in  by  the  sticky  dough.  If 
the  yeast  plant  is  well  distributed,  the  gas  collects  in 
many  small  bubbles,  and  the  loaf  is  fine-grained.  The 
alcohol  keeps  other  plants  from  growing  there,  and  also 
helps  to  soften  the  gluten. 

When  the  loaf  is  put  into  the  oven,  the  heat  kills  the 
yeast  plant,  drives  off  the  carbon  dioxide,  and  causes  the 
alcohol  to  evaporate.  The  heat  changes  the  gluten  into 
a  substance  more  easily  digested  and  of  a  more  pleasant 
taste.  In  "salt  rising'  bread  bacteria  from  the  air, 
instead  of  yeast  cells,  form  the  gas  which  makes  the 
bread  light.  When  a  batch  of  bread  "sours,"  it  is 
usually  because  harmful  bacteria  get  into  the  dough  ami 
grow  more  rapidly  than  the  yeast  plants.  Sometimes 
other  kinds  of  yeasts  than  the  helpful  ones  employed  in 
bread-making  accidentally  get  into  the  batch  of  bread  and 
it  spoils  as  a  result. 


180  LIFE   PROCESSES  OF  MAN 

149.  Adulteration  of  Foods.  — Foods  are  adulterated  either 
by  subtracting  some  of  the  nutritious  parts  and  substitut- 
ing less  valuable  parts,  or  by  adding  materials  which  can- 
not act  as  a  food. 

The  food  formerly  subject  to  the  most  adulteration  was 
milk.  This  adulteration  was  done  by  adding  water  to 
make  the  milk  go  farther  when  being  measured  out,  and 
adding  formalin  (for'ma-lin)  to  make  it  keep  sweet. 

For  a  time  many  of  the  cereals  were  adulterated  with 
sawdust,  peanut  shucks,  or  bran.  Many  of  the  special 
foods  put  up  in  packages  used  to  be  adulterated,  and  it 
would  require  a  long  description  to  enumerate  all  that 
have  been  found  unsatisfactory  for  food  by  the  Depart- 
ment of  Agriculture. 

Pure  Food  Laivs.  —  Congress  in  1906  passed  what  is 
known  as  the  Pure  Food  and  Drug  Law.  This  law 
requires  manufacturers  of  food  and  medicine  to  state  on 
the  label  what  is  in  each  package  or  bottle.  This  enables 
one  to  know  just  what. he  is  buying. 

150.  Indigestion.  —  Few  children  that  have  an  oppor- 
tunity to  romp  and  play  out-of-doors  and  have  plenty  of 
simple  and  plain  food  ever  experience  any  ill  feeling  in 
the  digestive  canal.  However,  as  children  grow  older, 
exercise  less,  and  eat  richer  food,  they  may  suffer  much 
inconvenience  from  indigestion. 

Indigestion  is  a  condition  which  rarely  extends  to  all 
parts  of  the  digestive  canal;  it  is  located  either  in  the 
stomach  or  in  the  small  intestine.  This  may  indicate  that 
certain  kinds  of  food  are  not  properly  digested.  Indiges- 
tion may  be  caused  by  eating  the  wrong  kinds  of  foods 
or  by  overloading  the  stomach.  If  the  food  is  chewed 
thoroughly,  the  appetite  is  usually  a  safe  guide  as  to  the 
amount  needed  by  the  body.  Moreover,  food  thoroughly 
chewed  is  more  easily  acted  upon  by  the  digestive  fluids. 


INDIGESTION  181 

To  some  people  certain  foods  are  indigestible  at  all 
times,  while  other  foods  are  indigestible  only  at  special 
times.  We  should  learn  to  understand  our  bodies  in  this 
particular.  Some  of  the  causes  of  indigestion  are:  lack  of 
sufficient  regular  exercise,  too  much  rich  food,  and  the 
failure  to  drink  enough  water. 

Students  and  professional  men  use  their  brains  more 
than  their  muscles,  but  they  require  protein  to  repair 
nerve  waste  just  as  laborers  require  proteins  to  feed 
their  tired  muscles.  Unless  students  and  professional  men 
exercise  their  muscles,  they  do  not  feel  vigorous  and  eager 
for  their  work.  On  the  other  hand,  unless  the  laboring 
men  exercise  their  brains,  they  do  not  do  their  work  as 
well  as  they  might.  The  amount  of  exercise  required 
varies  with  the  individual.  The  best  way  to  prevent  in- 
digestion is  to  have  regular  habits  of  eating  and  exercising. 

There  are  in  the  market  many  tablets  and  remedies  for 
indigestion,  which  may,  for  example,  contain  pepsin  and 
pancreatin.  Now  we  know  that  these  substances  when 
found  in  the  pancreatic  fluid  act  in  an  alkaline  medium. 
As  these  tablets  must  first  pass  into  the  stomach,  which  is 
an  acid  medium,  the  action  of  the  pancreatin  is  probably 
destroyed  long  before  the  remedy  reaches  the  intestine 
where  it  would  naturally  act.  This  means  that  such 
tablets  are  largely  useless  and  is  one  of  the  reasons 
why  many  doctors  believe  that  digestive  tablets  are  doing 
more  to  cause  indigestion  than  they  do  to  help  it.  There 
are  only  a  few  commercial  tablets  made  which  act  on  the 
undigested  foods  of  the  intestine.  No  medicine,  in  fact, 
can  give  permanent  relief  to  indigestion.  Predigested 
foods,  a  recent  attempt  to  relieve  indigestion,  serve  a 
useful  purpose  in  cases  of  sickness,  but  in  our  regular 
life,  should  be  used  sparingly  because  they  do  not  give  the 
digestive  organs  the  proper  amount  of  work  to  do. 


182  LIFE   PROCESSES  OF  MAN 

151.  Effect  of  Alcohol  on  Digestion.  —  Alcohol  taken  into 
the  digestive  tube  is  closely  related  to  the  question  of  in- 
digestion. The  lining  (mucous  membrane)  of  the  stomach 
and  intestine  is  delicate  and  tender,  and  contains  thousands 
of  cells  which  secrete  the  gastric  juice,  and  many  more 
thousands  that  help  to  digest  the  food.  When  alcohol 
comes  in  contact  with  these  delicate  cells,  it  prevents  them 
from  doing  their  normal  work.  The  result  is  that  food  is 
not  properly  digested. 

Indigestion  disguised  by  alcohol  *but  not  cured.  —  It  is  a 
serious  error  to  regard  alcohol  as  a  genuine  remedy  for 
indigestion  or  abdominal  pain.  It  is  true  the  sense  of 
pain  is  sometimes  abolished  by  alcohol,  and  as  a  result  of 
this  many  a  man  believes  that  alcohol  aids  his  digestion, 
whereas  it  merely  exerts  a  numbing  effect  on  the  stomach 
nerves,  and  his  indigestion  is  disguised  rather  than  removed. 
In  fact,  instead  of  being  cured  the  mischief  is  increased 
since  digestion  is  retarded.  Some  digestive  medicines 
contain  enough  alcohol  to  be  injurious.  Alcoholic  drinks 
taken  with  meals  make  the  food  hard  to  digest  because  the 
alcohol  makes  the  food  tough. 

SUMMARY 

Man  is  able  to  live  in  all  climates  and  localities  on  the 
earth.  No  plant  or  other  animal  can  do  this.  Man  con- 
trols his  surroundings.  Plants  and  animals  are  controlled 
by  their  surroundings.  Like  other  animals,  man  passes 
tli rough  the  periods  of  growth  known  as  youth,  maturity, 
and  old  age. 

Man  has  a  definite  set  of  digestive  organs  that  are  more 
highly  developed  than  those  of  any  other  animal.  These 
digestive  organs  prepare  proteins,  carbohydrates,  and  fats 
so  that  they  pass  into  the  blood.      The  blood  is  forced 


QUESTIONS  183 

by  the  heart  through  definite  blood  vessels.  The  study  of 
food  is  important  because  we  require  food  in  order  t<>  Live. 
The  cost  of  food  and  the  amount  needed  are  problems  that 
science  is  helping  to  solve. 

QUESTIONS 

How  does  man  differ  from  other  animals  in  regard  to  the  places  where 
he  lives  ?  Why  ?  What  do  man  and  other  animals  require  in  order  to 
grow?  Name  the  kinds  of  foods.  What  is  the  value  of  protein?  <>t 
carbohydrates  ?  What  does  cooking  do  to  foods  ?  Why  is  this  important  '.' 
What  is  digestion  ?  What  is  indigestion?  Absorption?  How  are  the 
cells  of  the  body  fed  ? 


CHAPTER   XVI 


SKELETON  AND  MUSCLES 

152.  Skeleton  and  Muscles.  —  Muscles  which  serve  to 
move  the  body  cover  and  protect  the  skeleton  of  man.  The 
more  delicate  organs  of  the  body  are  protected  further 
—  the  heart  and  lungs  by  the  ribs,  and  the  brain  by  the 

cranium.     The  skeleton 


nasal    bones 

clavicle  (collarbone! 
shoulder  blode 

nu  rntrus 


vCrani  u  m 
•  V-j-Ma'ar   (cheek)  bone 

-superior  maxillary    bones 

■       mferior 


and  muscles  of  man  are 
similar  to  the  correspond- 
ing parts  in  the  frog  and 
the  dog.  Certain  tech- 
nical differences  are 
noted  by  anatomists,  but 
in  general  plan  or  struc- 
ture and  in  their  func- 
tions, the  skeleton  and 
muscles  are  alike  in  all 
the  higher  animals. 

153.    The     Skeleton. — 
Unlike  the   rest    of   the 
body  the  skeleton  proper 
is  hard.     It   consists   of 
bone    and    a     compara- 
tively     soft      substance 
known    as    cartilage,  or  gristle.     There  are   cells    in  the 
bones  just  as  there  are  cells  in  the  liver,  the  muscles,  and 
in  the  nervous  system.     So,  like  the  other  parts  of  the 

184 


JV—  phalanges 


Figure  191.  —  Skeleton. 


THE   SKELETON 


IS") 


Figure  193.  -  -  Dia- 
gram of  Bone 
Structure. 


Figure  192. 


mlcrophotograph  of 
Bone. 


<© 

«w    ^> 

<5D 

<JS 

s 

® 

Compare  Figure   193. 


Figure   194.  —  Car- 
tilage. 


body,  the    bones   grow  because  the   individual    cells    are 
supplied  with  food  from  the  blood. 

Cartilage  occurs  near  the  ends  of  the  bones,  in  the  ear, 
and  in  the  nose.  It  is  especially  prominent  in  the  wrists 
and  ankles  of  children.  Therefore  children  should  not 
be   lifted    by   their  hands   nor   allowed  to   stand   until   a 


Figure  195.  —  X-ray  of  a  Normal  and  a  Broken  Elbow. 


186 


SKELETON  AND  MUSCLES 


certain  amount  of  bone  has  taken  the  place  of  this  soft 
cartilage. 

When  the  bone  of  a  limb  is  broken  the  physician  sets  it, 
Le.  places  the  broken  ends  together,  and  puts  splints  on 
the  limb  to  keep  the  parts  from  slipping  until  the  new  bone 
has  formed  and  hardened. 

The  joints  of  the  bones  of  the  arms  and  legs  allow  move- 
ments in  many  directions.     The  tearing  or  stretching  of 


Figure  196.  —  X-ray  of 
Hand  of  Child. 


Figure  197.  —  X-ray  of  Hand  of  Adult. 


the  structures  which  hold  the  bones  together  at  the  joints 
is  called  a  sprain.  The  joints  in  the  spinal  column  allow 
only  a  limited  movement,  while  the  joints  in  the  cranium 
are  immovable  and  some  of  its  bones  gradually  grow 
together. 

The  erect  position  of  man  gives  to  his  skeleton  important 
characteristics  which  the  skeletons  of  other   animals    do 


THE   XKELKTOS 


is? 


Figure   198. 
Broken  Femur. 


Figure  199. 
Same  Bone  Ten  Weeks  Later. 


Notice  the  large  "callus"  of  newly  forming  bone.     An  illustration  of 
a  poorly  set  bone.     The  broken  ends  of  the  bone  should  match.     (Potter.) 

not  possess.  Among  these  may  be  mentioned  the  curves 
in  the  spinal  column,  the  large  hip  bones,  and  the  heel  and 
arch  of  the  foot. 

STUDENT   REPORT 
Make  a  report  on  the  skeletal  structures  of  animals  as  follows : 

External 


Parauioeeium 

Crayfish     .     . 
Clam     . 
Frog      .     . 
Man,  etc.  .     . 


Absent 


JOIN!  ED 


\.  1 1 

.i.n s  1 1  n 


HOENl 


I '-  ■  \  -. 


Internal 


188 


SKELETON  AND   MUSCLES 


LABORATORY   STUDY 

Study  the  skeleton,  and  examine  long,  flat,  and  irregular  bones.     How  is 

the  bone  modified  to  do  its  work  ? 

154.    Muscles.  —  The  muscles  are  the  lean  parts  of  the 

flesh  of  animals  and  are  usually  dark  in  color.     Birds  are 

an  exception,  for  their  breast  meat 
is  generally  white.  Muscles  are  of 
two  kinds :  voluntary  (governed  by 
the  will),  such  as  those  which  we 
use  in  walking,  or  in  moving  the 
arms ;  involuntary,  such  as  those 
which  move  the  food  along  the 
digestive  tract  or  assist  in  breathing. 
The  voluntary  muscles  consist  of 
many  long  muscle  cells  (fibers) 
bound  together  into  a  distinct 
bundle.  Usually  the  muscle  bundle 
is  attached  at  each  end  to  the  bones. 
A  single  muscle  moves  the  arm  in 
one  direction  only,  and  in  order  to 
lift  the  arm  from  the  desk  to  the 
head,  for  instance, 
several  muscles 
must  act  together. 
The  cells  of  the 
involuntary  mus- 
cles are  unlike  the 
cells  of  the  volun- 
tary muscles.  In- 
voluntary muscle  cells  occur  in  la}rers 

in  the  walls  of  the  digestive  tube,  blood 

vessels,  the  bladder,  and  the  like,  and 

they  are  not  under  the  control  of  the 

will. 


Figure  200.  —  Muscles 
of  Upper  Leg. 

Note  how  they  are  ar- 
ranged in  bundles. 


Figure  201. — Vol- 
untary Muscle 
Cells. 


Showing  how  the 
cells  are  bound  to- 
gether with  connec- 
tive tissue.  At  the 
end  of  the  muscle, 
the  cells  of  the  con- 
nective tissue  form 
the  tendon. 


THE   SKIN 


IS!) 


Figure  202. 


-  Involuntary  Muscle 
Cells. 


The  muscular  tissue  of  the  heart  has  characteristics  of 
both  the  voluntary  and  involuntary  muscles,  so  that  it 
may  almost  be   said   to 


belong  in  a  special  class. 
155.  Skin.  — The  skin 
covers  and  protects  the 
voluntary  muscles,  regu- 
lates the  body  tempera- 
ture, gives  off  waste  matter,  and  acts  as  a  general  sense 

organ.  The  outer  layer  of 
skin  is  called  the  epidermis, 
and  is  chiefly  composed  of 
dead  cells.  These  outer  cells 
are  constantly  breaking  off,  a 
process  which  is  most  apparent 
in  the  case  of  sunburn.  What- 
ever pigment,  or  coloring  mat- 
ter,  there  is  in  our  skin  is  located  in  the  inner  cells  of 


Figure  203.  —  Heart  Muscle 
Cells. 


$BS! 


,-.    -    -  


Milk  . 

Figure  204.  —  Various  Forms  of  Cells  in  Human  Body. 

a.  side  and  top  view  of  flat  epithelium  :  b,  c,  columnar  epithelium 
d,  e,  ciliated  epithelium.  How  do  these  cells  differ  from  the  muscle 
cells  in  Figures  201-203? 


190 


SKELETON  AND   MUSCLES 


Epidermis 


lerve 


apilla 


pap 


the  epidermis.  The  amount  and  kinds  of  pigment  deter- 
mine whether  a  person  is  of  light  or  dark  complexion, 
white,  black,  or  yellow.  These  inner  cells  are  constantly 
crowing  new  cells  to  replace  the  cells  which  scale  off. 

The  nails  and  the  hair  arise  in  the  outer  layer  of  the 
skin.     Other  structures  which  arise  in  the  same  way  are 

the  scales  of  fishes  and 
snakes,  the  hoofs  and 
horns  of  cattle,  and  the 
feathers  of  birds. 

The  inner  layer  of  the 
skin  is  the  dermis,  and 
contains  blood  vessels, 
nerves,  connective  tissue, 
the  sweat  glands,  and 
sense  organs  of  touch.  It 
is  estimated  that  there 
are  over  two  million  sweat 
glands  in  the  skin  of  a 
man.  Their  work  is  to 
eliminate  waste  sub- 
stances from  the  blood  and  to  keep  the  body  temperature 
normal  (98.4°  F.)  by  regulating  the  amount  of  perspira- 
tion excreted.  The  amount  of  perspiration  is  influenced 
both  by  the  temperature  of  the  body  and  of  the  air.  The 
evaporation  of  perspiration  keeps  the  body  at  the  normal 
temperature. 

SUMMARY 

Man  has  a  skeleton  covered  by  muscles  and  skin.  The 
bones  grow  and  are  fed  just  like  the  muscles.  This  is 
proved  when  the  broken  bone  heals.  The  muscles  are 
the  flesh  covered  by  the  skin.  The  muscles  are  both 
voluntary    and    involuntary.     The    skin   is   made    up  of 


Dermis 

Nulnlive 
paoilla 

Sweai    &land 
Nerve 

ood  vessels 


Figure  205.  —  Diagram  of  Skin. 


QUESTIONS  191 

several  layers  of  cells.    'Nails  and  the  hair  grow  from  the 
outer  layers.     The  sense  of  touch  is  in  the  skin. 

QUESTIONS 

How  does  the  skeleton  of  man  compare  with  the  skeleton  of  the  cray- 
fish? How  do  bones  grow?  Why  do  they  grow?  When  is  there  the 
most  cartilage  in  our  skeletons ?  How  many  kinds  of  muscle  are  there? 
What  is  the  work  of  each  ?  What  is  the  work  of  the  skin  ?  Of  what  is 
the  skin  composed  ? 


CHAPTER   XVII 

RESPIRATION,  BLOOD,  AND  EXCRETION 

156.  Respiration  is  the  life  process  in  which  oxygen  is 
used  in,  and  carbon  dioxide  eliminated  from,  the  cells  of 
the  bodies  of  plants  and  animals.  All  animals  carry  on 
respiration,  and  in  all  the  process  is  alike,  although  the 
various  animals  use  different  structures  to  secure  the  inter- 
change of  oxygen  and  carbon  dioxide.  The  hydra  and 
earthworm  use  the  entire  surface  of  the  body  in  this 
process ;  the  fish  has  special  organs,  the  gills,  while  the 
frog  and  man  have  lungs. 


Student  Report  on  Respiration 


Get  Oxygen 

Get  Kid  of 
Carbon  Dioxide 

Breathe  Through 

Water 

Air 

Water 

Air 

Skin 

Gill 

Lung 

Air 
tubes 

Leaves 

Amoeba 

Crayfish 

Fly 

Clam 

Toad 

Bird 

Man 

Bean 

Yeast 

In  order  to  help  comparison  the  teacher  may  explain  about  the  plant. 

Organs  of  Respiration  in  Man.  —  Air   enters   the   nose 
and  passes  into  the  windpipe  or  trachea  (tra/ke-a).     The 

192 


ORGANS  OF  RESPIRATION 


VXi 


opening  into  the  windpipe  is  covered  by  the  epiglottis 
(Greek,  epi,  upon;  glotta,  tongue),  which  is  raised  dur- 
ing breathing  and  closed  when  food  is  swallowed.  The 
windpipe  divides  into  two  branches,  one  entering  each 
lung.  Each  branch  is  called  a  bronchus.  The  windpipe 
and  bronchi  are  the  air  passages  which  cany  air  to  the 
lungs.  These  passages  are  kept  open  by  numerous  stiff 
cartilage  rings,  which,  in  the  trachea,  are  not  entirely 
complete  on  the  side  of  the 
esophagus,  and  in  the  smaller 
tubes  even  less  so. 

On  entering  the  lung  each 
bronchus  divides  into  branches 
which  in  turn  branch  out  again 
and  again,  until  the  entire  lung 
is  penetrated  in  all  its  parts  by 
these  passages.  Finally  each 
branch  ends  in  a  small  pouch- 
like sac  called  an  air  cell.  The 
walls  of  the  air  cells  are  thin, 
and  the  cells  themselves  are 
surrounded  by  minute  branches 
of  the  blood  vessels.  It  is  esti- 
mated that  the  highly  folded  condition  of  the  walls  of  the 
bronchi  make  a  surface  larger  than  the  entire  surface  of 
the  body.  All  these  thin  walls  of  the  lungs  and  blood 
vessels  are  adapted  to  the  passage  of  oxygen  into  tin- 
blood. 

The  lungs  of  man,  then,  consist  of  two  large  bronchial 
air  tubes,  many  brandies  of  the  bronchi,  air  cells,  blood 
vessels,  and  a  few  nerves,  all  bound  up  into  two  definite 
bodies  (Figure  206). 

The  voice  box  or  larynx  (la r' inks')  is  found  just  below 
the   opening   into   the   windpipe   and    is   called   "  Adam's 


Figure  206.  —  Lungs  and 
Heart. 

Note  the  branches  of  the 
bronchus  and  blood  vessels  on 
the  right  side. 


194        RESPIRATION,   BLOOD,   AND  EXCRETION 

apple."     The  larynx  is  formed  by  several  large  pieces  of 
cartilage  lined  with  a  mucous  membrane.     On  the  inside 


ical  cords 
trachea 

During     Respiration  During   Phonafion 


Figure  207.  —  Voice  Box  or  Larynx. 


of  the  larynx  project  two  folds  of  elastic  tissue  which  are 
called  the  vocal  cords. 

157.  Breathing.  —  The  lungs  are  elastic  and  can  be 
squeezed  like  a  sponge.  Inspiration  is  the  term  applied 
to  the  taking  of  air  into  the  lungs,  and  expiration  to  the 
forcing  out  of  air.  When  air  is  drawn  into  the  lungs, 
the  chest  expands,  and  the  diaphragm  (Figure  208),  the 
horizontal  muscle  which  divides  the  lung  cavity  from  the 
abdomen,  is  drawn  down.  Thus  the  chest  cavity  is  en- 
larged and  air  is  sucked  into  the  lungs.  In  expiration 
the  air  passes  out  gently. 

When  we  breathe  naturally,  only  a  small  part  of  the 
air  in  the  lungs  is  exchanged  at  each  inspiration  and  ex- 
piration, but  by  breathing  deeply  a  few  times  we  can 
remove  the  larger  part  of  the  air  from  the  lungs  and  re- 
place it  with  fresh  air. 

The  natural  rate  of  breathing  is  about  eighteen  times  a 
minute,  but  the  rate  is  higher  in  persons  with  a  small  lung 
capacity.     Exercise  increases  the  rate  of  breathing.     Ex- 


BREATHING 


L95 


plain  why  exercise  out-of-doors  is  better  for  us  than   that 
taken  indoors. 

All  the  air  passages  are  lined  with  cells  bearing  numer- 
ous cilia  (Figure  204),  and  these  cilia  are  constantly  in 
motion.  Their  work  is  to  carry  toward  the  mouth  the 
particles  of  dust  and  other 
foreign  materials  brought  in 
by  the  air.  This  foreign  matter 
is  removed  when  we  cough  or 
clear  our  throats.  Explain  why 
clean  air  is  better  for  us  than 
dirty  air. 

The  air  that  enters  the  lungs 
is  rich  in  oxygen  and  there  is 
some  oxygen  in  the  air  which  is 
expired.  But  the  proportion  of 
carbon  dioxide  is  greater  in 
the  expired  air  of  plants  and 
all  animals. 

Ventilation. — Associated  with 
the  question  of  breathing  is  the 
problem  of  supplying  our  homes 
with  fresh,  clean  air.  Every 
one  feels  better  after  a  walk  in  the  open  air.  How  to 
have  plenty  of  fresh  air  in  our  rooms  is  a  diilieiilt  problem. 
One  of  the  difficulties  is  to  get  the  air  down  to  the  breath- 
ing line  and  not  stir  up  the  dust  on  the  floor.  Figures 
209  and  210  show  the  best  plans  for  ventilating  a  room. 
They  are  adapted  to  the  two  common  methods  of  heating, 
hot  air  and  steam  or  hot  water.  They  show  the  coins.'  I aken 
by  the  currents  of  fresh  air  entering  the  room  at  night  with 
the  window  open,  and  in  the  daytime  with  it  shut. 

Exercise.  —  Even   if  the  home   is   furnished   with   fresh 
air,  we  should  observe  good  habits  of  breathing.      When 


a. -Oesophagus 

b. -Diaphragm 


Figure  208.  —  Diagram  of 
the  Diaphragm. 

Note  the  position  at  the  bot- 
tom of  the  thorax. 


196         RESPIRATION,   BLOOD,   AND   EXCRETION 


POOM  AT A//6//7" 
/vowecr  HSJrwG. 


we  walk  out-of-doors,  we  should  take  plenty  of  fresh  air 
into  our  lungs  in  a  series  of  deep  breaths.  All  young 
people  should  take  exercise  in  the  open  air,  because  such 
exercise  develops  all  the  organs  and  makes  them  strong. 
Thus  the  whole  body  becomes  more  robust  and  better  able 

to  withstand  disease  and 
to  do  its  work. 

Suffocation.  —  When 
the  body  is  deprived  of 
a  sufficient  supply  of 
oxygen,  suffocation  re- 
sults. This  is  what 
happens  in  drowning  or 
when  the  windpipe  be- 
comes closed. 

In  many  cases  a  per- 
son who  is  suffocating 
may  be  saved  through 
artificial  respiration. 
This  is  the  name  given 
to  a  series  of  movements 
which  are  used  to  restore 
natural  breathing.  The 
simplest  method  is  to 
place  the  patient  on  his 
back,  with  the  head 
lower  than  the  hips. 
Then  raise  the  arms  upward  and  outward  until  they  come 
together  above  the  head.  This  movement  enlarges  the 
chest  cavity  and  helps  to  draw  air  into  the  lungs.  The 
air  is  forced  out  of  the  lungs  by  bringing  the  arms  back  to 
the  side  of  the  body  and  pressing  gently  against  the 
sides  of  the  chest.  This  series  of  movements  should  be 
repeated   gently   every   few   seconds,  and    may   have    to 


f '-^^•^^^=^gr3Kgggsj5^^"^a^.^ va 'x--:'- ■;'-  -^ 


Room  /HD4vr//v£ 

/A/PW£Cr  H£jr/A/G. 

Figure  209.  —  Hot-air  Heating. 
By  Earl  Hallenbeck. 


BLOOD 


197 


#OOM  AT  A//GWT 
£>//?£  CT    HEJT/HG 


be    continued    for    hours    before    natural     breathing    is 
restored. 

Diseases  of  the  Respiratory  Tract.  —  The  most  common 
of  these  diseases  is  a  cold  located  in  the  nose  and  throat. 
The  nasal  passages  be- 
come clogged  with 
mucus  which  contains 
many  germs.  These 
germs  are  widely  distrib- 
uted in  sneezing. 

Diphtheria  is  a  germ 
disease  which  is  located 
in  the  throat  and  nose. 
For  many  years  diph- 
theria was  one  of  the 
most  deadly  of  our  dis- 
eases, but  through  the 
use  of  the  diphtheria 
antitoxin  the  danger  has 
been  greatly  reduced. 

Tuberculosis  of  the 
throat  and  lungs  is  a 
widely  distributed  dis- 
ease which  causes  many 
deaths  each  year.  See 
page  235. 

158.  Blood. — The  blood  is  the  fluid  which  circulates 
through  the  heart,  arteries,  and  veins,  supplying  nutritive 
material  to  all  parts  of  the  body.  Blood  is  made  up  of  a 
fluid  (plasma)  which  contains  cells  or  corpuscles  (  Latin, 
corpuseulum,  little  body).  The  blood  cells  or  corpuscles 
are  of  two  kinds,  red  and  white. 

The  red  corpuscles  are  colored  with  a  substance  called 
haemoglobin  (he-mo-glo'bin:    (iivek,  haima,  blood:   globus, 


BR£ATHIN6     LIN£ 


■ 
-  OUT 


i- 


- 


Room  //vD^yr//V£ 

£)/&£  c  T    H£A  T/HG 

Figure  210.  —  Steam  Heating. 
By  Earl  Hallenbeck. 


198        RESPIRATION,   BLOOD,   AND  EXCRETION 


Figure  211.  —  Micro- 
photograph  of  Blood 
of  Frog. 


ball).     When   a   few   of   these    corpuscles    are    examined 

through  a  microscope,  they  appear  yellowish  instead  of 

red  ;  but  when  a  large  number  of 
them  are  seen  in  a  mass,  the  red 
color  is  apparent.  When  the  red 
cells  are  first  formed,  they  have  a 
nucleus  which  gradually  disappears. 
As  a  result,  the  mature  red  corpus- 
cles, unlike  all  the  other  cells  we 
have  studied  thus  far,  have  no 
nucleus.  Red  corpuscles  are  about 
3<>Vo  °^  an  incn  iR  diameter  and 
T2T0  o  °^  an  ^ncn  thick. 
The    red  corpuscles   carry  oxygen    from  the  lungs  to 

the    cells   of   the   body.     This   oxygen    unites    with    the 

haemoglobin.     By    osmosis   the   oxygen   passes   from    the 

blood  to  the  body   cells  which  are  deficient  in   oxygen. 

These  cells  take  the  oxygen  and  use  it  in  the  process  of 

oxidation,  which  goes  on 

continuously    in    every 

living     cell.       A     good 

supply     of     red     blood 

corpuscles  is,  therefore, 

necessary,  if  the  cells  of 

the  body  are  to  have  a  Figure  212. 

sufficient  supply  of  OXy-         As  the  blood  flows  through  the  capil- 

2"en.        The     feeding"     of     ^aries  which   are  found    in    all  voluntary 
.  ,,         .  ,  .       muscles,  for  example,   oxygen  and  other 

the  cells  with  oxygen  is    food  products  are  given  off  to  the  muscle 

One  part  of  respiration.       cells,     and     carbon     dioxide    and     other 

At  the  same  time  that    waste    substances    Pass    off    from    these 

same    muscle   cells    into   the    capillaries 

oxygen  is  received  from    on  the  way  int0  the  veins. 

the   blood  by  the  body 

cells,  carbon  dioxide  is  given  off.     Again  osmosis  explains 

the  method  of  this  transfer.     Most  of  the  carbon  dioxide  is 


BLOOD 


199 


Figure  213.  —  Organs  of  Circulation. 

Veins,  black  ;    arteries,  with  transverse  lines.     Left  side  of  figure  shows 
superficial  vessels,   while  right  side  shows  deeper  vessels. 


200        RESPIRATION,  BLOOD,   AND  EXCRETION 

carried  by  the  plasma,  although  some  of  it  unites  with  the 
haemoglobin. 

White  blood  corpuscles  are  much  like  the  amoeba  in 
that  they  are  colorless  and  can  change  their  form.  They 
move  about  in  the  body  and  often  leave  the  blood  vessels 
and  collect  at  one  place  to  aid  the  body  in  destroying 
disease  germs. 

The  blood  plasma  is  straw-colored  and  varies  in  compo- 
sition from  day  to  day,  and  hour  to  hour.  It  contains  the 
foods  on  their  way  to  the  cells  and  waste  products  on  their 
way  to  the  kidneys,  lungs,  or  skin. 

The  volume  of  blood  in  the  average  person  is  about  six 
quarts. 

When  exposed  to  the  air,  blood  forms  a  clot,  because  of 
the  presence  of  a  substance  (fibrinogen)  which  produces 
fibers  that  hold  the  red  and  white  corpuscles. 

Student  Report  on  Blood 


Name  of  Animals 


© 

N 
X 

o 
p-1 
o 
O 

H 

O 

a 

w 
« 
o 

Hi 

o 

Color  in 
Plasma 

CO 

C    P 

o  5 

o  o 

o 

*3 

►4 
W 
m 

H 

>— < 

w 

o 

03 


159.  Heart  and  Blood  Vessels.  —  The  blood  is  carried 
from  the  heart  to  all  the  cells  of  the  bodv  and  back  to  the 
heart  again  and  again.  The  heart  serves  as  a  pump  to 
force  the  blood  along.  The  heart  is  about  the  size  of 
the  fist  and  has  strong  muscular  walls.  In  a  healthy 
person,  it  contracts  regularly  about  seventy  times  a  min- 


HEART  AND  BLOOD    VESSELS 


201 


J*> 


ute.  It  is  obvious,  therefore, 
that  the  work  which  the  heart 
does  is  very  great.1 

The  heart  is  located  in  the 
thoracic,  or  chest  cavity,  a  little 
to  the  left  side  and  between  the 
lungs.  It  is  a  cone-shaped  organ, 
inclosed  in  a  membranous  bag" 
called  pericardium  (per-i-car'di- 
um  :    Greek,  peri 

U  around  ;        cardia, 

heart). 

The  heart  is 
divided  by  a  wall 
into  right  and  left 

chambers.  A  nearly  complete  cross  parti- 
tion divides  each  side  into  upper  chambers, 
the  auricles,  and  the  lower  ones,  the  ventri- 
cles. The  opening  between  an  auricle  and 
a  ventricle  is  guarded  by  a  valve,  which  is 
partly  membranous  and  partly  muscular. 
The  auricles  receive  blood  from  the  veins, 
while  the  ventricles  force  blood  into  the 
arteries. 
Artery  is  the  name  given  to  the  blood  vessels  which 
carry  blood  from  the  heart,  and  vein  is  the  term  applied 


Figure  214.  —  Heart. 


Figure  215 
Diagram 
Vein. 


of 


Showing  the 
valves. 


1  "  The  work  the  heart  does  during  the  day  is  about  equal  to  the  energy 
expended  by  man  in  climbing  to  the  top  of  a  mountain  3600  feet  high. 
Assuming  that  the  man  weighs  about  150  pounds,  this  would  be  equal  to 
an  amount  of  energy  sufficient  to  lift  00  tons  to  a  height  of  three  feet 
The  work  of  the  left  side  is  greater  than  that  of  the  right,  since  the 
former  has  to  drive  the  blood  all  over  the  body,  while  the  latter  baa  only 
to  force  it  to  the  lungs  which  are  near  by.  For  this  reason  the  muscle 
walls  of  the  right  ventricle  are  much  thinner  than  those  of  the  left 
ventricle."  —  Conn  and  Buddington. 


202         RESPIRATION,   BLOOD,   AND   EXCRETION 


Figure  216.  —  Diagram  of  Capillaries. 

The  artery  breaks  up  into  minute 
branches,  the  capillaries,  which  in  turn 
unite  to  form  veins. 


to  the  vessels  which  return  blood  to  the  heart.      There  is 
little  structural  difference  between  the  veins  and  arteries 

except  that  the  walls  of 
the  arteries  are  thicker, 
and  there  are  no  small 
valves  as  in  the  veins. 
As  the  branches  of  the 
arteries  become  minute, 
the  walls  become  much 
thinner,  thus  allowing 
the  food  and  oxygen  to  pass  more  easily  to  the  individual 
cells.  These  minute  branches  are  called  capillaries 
(Latin,  capillus,  hair).  From  a  cluster  of  capillaries  a 
small  vein  begins  which  soon  connects  with  a  slightly 
larger  vein,  which  leads  back 
to  the  heart  through  larger 
and  larger  veins. 

The  blood  follows  a  regular 
course  through  the  body,  pass- 
ing from  the  left  ventricle  into 
the  aorta,  which  is  the  largest 
artery  in  the  body.  As  soon 
as  the  aorta  leaves  the  heart, 
smaller  arteries  branch  from  it, 
and  the  aorta  itself  also  branches 
until  the  entire  body  is  sup- 
plied with  blood.  The  right 
ventricle  gives  off  a  short 
arterv  which  divides,  and  a 
branch  enters  each  lung.  At 
the  point  where  an  artery 
leaves  a  ventricle,  there  are  three  half -moon-shaped  valves 
which  prevent  the  blood  from  flowing  back  into  the  heart 
(Figure  215). 


To  Brain 

To  Skin 
--To  Arm 
"-To  Lung 


To  Kidneys^ 


To  Stomach 

•To  Small 
Intestine 


:_ ";:To  Back 

To  Large  Intestine 
-To  Leg 


Figure  217.  —  Main  Arteries 
of  Frog. 


HEART  AND  BLOOD    VESSELS 


21  >3 


I  0  I 


All  to  Back 


4^;;^  To  stomach 

- 

— 

\  To  Kid- 

'  p^-^Jo  Reproductive 
organs 

To  L.i 

■ 


The  blood  which  is  carried 
into  the  lungs  contains  a  large 
amount  of  carbon  dioxide 
which  gives  it  a  dark  color. 
In  the  lungs  the  carbon  dioxide 
is  given  off  and  oxygen  taken 
up,  so  that  when  this  blood  is 
returned  to  the  left  auricle,  it 
is  of  a  bright  red  or  "  arterial " 
color. 

Every  time  the  heart  beats 
the  blood  is  forced  into  the 
arteries  in  waves  which  can  be 
felt  in  the  wrist  or  neck  by 
placing  the  finger  over  an 
artery.  The  wave  is  called 
the  pulse.  By  counting  the 
number  of  waves  each  minute, 
the  rate  at  which  the  heart  beats 
is  determined.  When  a  person 
runs  or  takes  violent  exercise, 
the  pulse  rate  increases.  It 
is  advisable  to  know  what  our  usual  pulse  rate  is,  for 
an  increased  pulse  rate  is  sometimes  an  indication  of 
approaching  illness. 

Lymph. — As  the  blood  flows  through  the  capillaries, 
part  of  the  plasma  passes  through  the  thin  walls  into  the 
spaces  between  the  cells  and  bathes  the  cells.  This  fluid 
which  escapes  from  the  capillaries  is  called  lymph  (llmf). 
It  is  composed  of  digested  food,  water,  and  other  sub- 
stances. The  cells  take  up  the  food  which  they  nerd 
and  cast  back  into  the  lymph  the  wastes  which  they  have 
formed  in  the  process  of  growth  and  repair.  These  spaces 
between  the  cells  are  small  and   irregular  in  shape.     The 


To  Legs 


Figure  218.  —  Main  Arteries 
of  Man. 

Compare  with  Figure  217. 


204         RESPIRATION,   BLOOD,   AND  EXCRETION 

spaces,  however,  form  a  sort  of  mesh,  or  net,  the  parts  of 
which  join,  forming  larger  vessels,  and  finally  all  the 
lymph  is  collected  into  two  large  vessels  which  open 
into  veins.  Thus  there  is  the  lymphatic  circulation  which 
differs  from  that  of  the  blood  in  several  ways.  (1)  There 
is  no  special  organ  for  forcing  the  lymph  along,  the  circula- 
tion depending  mainly  upon  the  movement  of  the  muscles. 


Figure  219.  —  Superficial  Lymphatics  of  Arm  and  Hand. 

(2)  The  lymphatic  vessels  are  imperfect  in  the  beginning, 
being  only  irregular  spaces.  (3)  The  lymph  contains 
no  red  corpuscles  and  only  a  few  white  corpuscles. 

Cuts.  — Since  every  part  of  the  body  inside  the  skin  is 
traversed  by  blood  vessels,  we  cannot  injure  any  part 
without  breaking  at  least  some  of  the  blood  vessels.  A 
small  cut  causes  the  blood  to  flow  only  from  capillaries, 
and  it  flows  slowly  and  in  small  quantities.  If  a  vein  is 
cut,  the  blood  will  be  dark  in  color,  and  will  flow  in  larger 
quantities,  but  steadily.  A  severed  artery  sends  out 
bright  red  blood  in  waves  corresponding  to  the  beat  of 
the  heart.  To  stop  the  flow  of  blood  from  a  vein,  com- 
press the  vein  beyond  the  cut  ;  from  an  artery  compress 
the  artery  between  the  cut  and  the  heart.  In  either  case 
remain  quiet  to  aid  the  blood  to  form  a  clot. 

Exercise.  —  The  object  of  a  circulatory  system  and  of  a 
circulatory  fluid  is  to  supply  every  cell  in  the  body  with 


HEART  AND   BLOOD   VESSELS  205 

food  and  to  carry  away  the  waste.  The  more  active  tin- 
process  of  circulation,  the  more  perfectly  is  this  object 
accomplished.  It  is  the  common  experience  that  the 
heart  beats  more  rapidly,  the  lungs  work  harder,  and  the 
body  becomes  warm  after  a  few  minutes  of  vigorous 
exercise.  These  changes  have  a  decidedly  beneficial 
effect  upon  building  up  the  body  and  removing  tin- 
wastes. 

In  most  kinds  of  work  only  one  set  of  muscles  is  used. 
This  set  gets  a  full  supply  of  blood,  but  others  get  less 
than  a  full  supply  and  so  they  get  too  little  food  and  ac- 
cumulate too  much  waste.  Every  one  should,  at  some  time 
in  the  day,  take  exercise  in  the  open  air  which  will  bring 
all  his  muscles  into  play.  If  it  is  enjoyable  exercise,  tin- 
effects  upon  the  mind  react  favorably  uj)on  the  body. 
This  is  the  advantage  of  such  exercises  as  skating  or 
baseball.  In  the  winter  it  often  requires  real  effort  to 
force  oneself  to  leave  a  warm  room  and  to  go  out  for  ex- 
ercise, but  if  one  is  properly  clothed,  cold  air  has  a  bracing 
effect  not  obtained  at  any  other  time  of  year. 

Fainting. — Fainting  is  due  to  an  insufficient  supply  of 
blood  in  the  brain.  This  lack  of  blood  may  arise  from 
several  causes,  but  the  most  common  is  some  disturbance 
of  the  digestive  processes,  which  causes  the  heart  to  beat 
too  slowly.  A  fainting  person  should  be  placed  flat  on 
his  back,  if  possible,  with  his  head  slightly  lower  than  the 
rest  of  his  body,  and  should  be  given  plenty  of  fresh  air. 
A  dash  of  cold  water  in  the  face,  or  a  bottle  of  ammonia 
held  to  the  nostrils,  is  often  helpful  in  restoring  conscious- 
ness. 

TJie  Effect  of  Drugs  and  Alcohol.  —  "The  flow  <>f  tin- 
blood  is  modified  by  various  drugs,  some  causing  the  blood 
to  flow  more  rapidly,  others  more  slowly.  Coffee  cans.  - 
the  heart  to  beat  harder  and  at  the  same  time  causes  some 


206         RESPIRATION,  BLOOD,   AND  EXCRETION 

of  the  arteries  to  become  smaller.  For  this  reason  it  is 
called  a  stimulant."  —Conn  and  Buddington. 

It  has  been  stated  frequently  that  alcohol  increases  the 
activity  of  the  heart.  Careful  experiment,  however, 
shows  that  not  only  is  the  effect  not  that  of  a  stimulant, 
hut  that  when  used  in  large  amounts,  it  markedly  weakens 
the  action  of  the  heart.  If  taken  only  in  small  amounts, 
the  heart  sometimes  shows  a  slight  increase  in  its  rate  of 
beating,  but  this  occurs  only  when  the  brain  becomes  ex- 
cited, and  if  the  person  is  kept  quiet  no  change  in  the 
heart  beat  is  noticeable.  Thus  the  primary  action  is  on 
the  brain. 

"  A  second  effect  of  alcohol  is  more  evident.  The  small 
blood  vessels  in  the  skin  are  enlarged.  This  produces  a 
flushed  skin,  a  feeling  of  warmth,  and  a  false  feeling  of 
increased  circulation.  Its  result  is  to  send  more  blood 
through  the  skin  with  consequent  extra  loss  of  heat.  This 
action  is  evidently  not  due  to  stimulation,  but  to  the  re- 
laxation of  the  muscles,  and  is  thus  a  decrease  of  activity 
rather  than  an  increase,  even  though  the  blood  does  flow 
a  little  more  rapidly  through  the  skin.  These  facts  make 
it  clear  that  alcohol  cannot  be  properly  called  a  stimulant 
of  the  circulatory  system."  —  Conn  and  Buddington. 

160.  Excretion.  —  Every  animal  uses  energy  in  carrying 
on  its  work.  During  this  process  a  certain  amount  of 
waste  substance  is  produced,  which  has  to  be  removed 
from  the  body.  The  skin,  kidneys,  and  lungs  are  the 
chief  organs  which  assist  the  body  in  getting  rid  of  this 
waste.  When  any  part  of  the  living  cells  is  broken  down 
in  the  simple  act  of  living,  a  waste  product  results.  By 
osmosis  these  waste  products  enter  the  blood  and  are 
removed  by  the  lungs,  which  give  off  carbon  dioxide;  by 
the  sweat  glands  in  the  skin;  and  by  the  kidneys,  which 
remove   the    wastes    that   contain    nitrogen.      The  sweat 


EXCRETION 


207 


glands  and  kidneys  are  usually  regarded  as  the  excretory 
organs  of  man.     These  organs  remove  from  the  blood  the 

wastes  which  have  been  excreted  by  the  cells  of  the  body. 
The  excretion  from  the  living  cells  is  one  of  tin*  funda- 
mental life  processes  of  all  plants  and  animals.  This  form 
of  excretion  should  not 
be  confused  with  the  in- 
digestible part  of  the 
food  which  is  not  taken 
up  by  the  blood  and 
which  passes  out  through 
the  large  intestine  as 
fseces. 

The  kidneys  are  two 
bean-shaped  organs  lo- 
cated in  the  abdominal 
cavity,  one  on  each  side 
of  the  "small"  of  the 
back.  Each  is  about 
four  inches  long,  two 
and  a  half  inches  wide, 
and  half  an  inch  thick. 
The  color  is  a  dark  red. 
The  kidney  is  made  up  of  two'  layers,  the  outside  or 
cortical,  and  the  inside  or  medullar  jf.  Each  layer  is  com- 
posed of  many  small  tubes  (tubules')  which  open  into  an 
area  called  the  pelvis}  the  space  within  the  kidney.  The 
pelvis  continues  into  a  duct  (ureter),  and  from  each 
kidney  the  ureter  passes  into  the  bladder.  A  small  duct 
(urethra)  connects  the  bladder  with  the  exterior  of  the 
body. 

Each  tubule  in  the  kidney  is  in  dose   relation  with  the 


Figure  220.  —  Section  of  Kidney. 


i  The  word  pelvis  is  also  used  in  referring  t«>  the  hip  bones,  and  it  Is  better 

to  call  the  latter  structure  the  bony  pelvis. 


208         RESPIRATION,   BLOOD,   AND   EXCRETION 


Arterrj 


uriniferous 
tubule 


Figure  221.  —  Diagram. 

Showing  relation  of  artery  and 
vein  to  portion  of  minute  kidney 
tube   (uriniferous  tubule). 


blood  capillaries.  At  the 
place  where  this  close  re- 
lation takes  place,  glomeru- 
lus (glo-meVu-lus),  the 
walls  of  the  capillary  and 
the  walls  of  the  kidney  are 
very  thin.  Through  these 
thin  walls  a  large  amount 
of  water  filters  out  of  the 
blood  into  the  tubes.  At 
the  same  time  waste  ma- 
terial which  contains  nitro- 
gen, salts,  and  other  organic 

wastes   is  removed.     If   these    wastes   are  not  removed, 

they  create  toxins  which  poison  the  body. 

SUMMARY 

All  living  things  breathe  oxygen  which,  in  the  higher 
animals,  is  carried  by  the  blood  to  the  cells  of  the  body. 
The  parts  which  man  uses  in  breathing  are  more  highly  de- 
veloped than  in  any  other  animal.  Man  has  a  voice  box,  the 
larynx,  by  means  of  which  he  is  able  to  make  a  wide  variety 
of  sounds.  The  blood  of  man  is  similar  to  the  blood  of  all 
the  other  vertebrates,  although  not  identical.  It  consists  of 
red  and  white  corpuscles  which  move  freely  in  the  plasma. 
The  blood  is  confined  in  the  blood  vessels  through  which  it 
is  forced  by  the  heart.  Excretion  includes  the  waste 
products  derived  from  living  protoplasm.  The  kidneys 
and  sweat   glands    remove    the   liquid   wastes   from    the 

blood. 

QUESTIONS 

Compare  the  respiration  of  man,  the  hydra,  and  the  earthworm.  Com- 
pare the  lungs  of  man  with  the  gills  of  a  fish.  What  is  blood  ?  What 
is  its  use  ?  What  is  the  difference  between  veins  and  arteries  ?  Explain 
the  work  of  the  kidneys  and  of  the  lungs 


CHAPTER    XVIII 

THE  NERVOUS  SYSTEM  OF  MAN 

161.  Parts  of  the  Nervous  System.  —  The  nervous  system 
of  man  consists  of  the  same  general  parts  as  the  nervous 
system  of  the  frog  (See  page  118).  There  is  a  brain  and 
spinal  cord,  from  which  nerves  extend  to  the  special 
senses,  the  muscles,  the  heart,  and  the  stomach.  When 
the  brain  of  man  is  compared  with  that  of  the  frog,  it  is 
obvious  that  the  cerebrum  of  man  is  proportionately  larger. 
Although  some  of  the  other  parts  of  the  brain  appeal 
unlike  the  corresponding  regions  in  the  frog,  scientists 
tell  us  that  they  are  really  the  same. 

162.  The  Nerve  Cell.  —  The  nervous  system  of  man  con- 
sists of  many  thousands  of  nerve  cells  which  differ  from  all 
other  cells  in  having  more  parts  and  branches  (Figures 
223,  224,  225).  The  nerve  cells  are  unlike  other  evils 
in  appearance,  although  they  have  the  usual  parts.  Ex- 
amination shows  that  the  nerve  cells  have  a  prominent 
nucleus  surrounded  by  cytoplasm,  which  grows  out  into  a 
number  of  branches  called  fibers.  The  shorter  branches 
divide  and  form,  together  with  the  branches  from  the 
neighboring  nerve  cells,  a  mass  of  tangled  fibers.  There 
is  usually  one  unbranched  fiber,  perhaps  several  feet  Long, 
which  ends  either  in  the  skin,  in  some  muscle,  or  in  tin- 
nervous  system.  When  this  long  liber  readies  the  muscle 
or  skin,  it  divides  into  several  fine  branches.  All  of  these 
branches  which  arise  from  a  nerve  cell  belong  to  it, and  in 
this  connection  the  word  cell  includes  all  the  branches, 
the  nucleus,  and  the  cytoplasm. 

209 


210 


THE   NERVOUS  SYSTEM   OF   MAN 


163.   The    Location    of    the    Nerves.  —  The    nerve    fibers 
which  have  the  same  work  to  do  occupy  certain  definite 

places  in  the  brain 
or  spinal  cord.  So 
a  student  of  the  nerves 
can  tell  the  route 
which  the  stimulus 
arising  from  feeling 
a  pencil  must  travel 
before  reaching  that 
part  of  the  brain  where 
it  is  interpreted  as  a 
pencil  ;  or  the  route 
over  which  the  stimu- 
lus arising  from  tast- 
ing candy  must  pass 
before  it  is  known  to 
be  candy.  When  we 
see  the  pencil  or  the 
candy,  the  route  over 
which  the  sight  stimuli 
of  these  two  objects 
travel  is  not  the  same 
as  that  of  the  feeling 
of  the  pencil  or  tasting 
the  candy.  The  nerve 
cells  which  interpret 
the  stimulus  arising 
from  feeling  the  pencil 
or  from  tasting  the 
candy  or  seeing  the 
pencil  and  the  candy 
are  probably  not  the  same.  We  may  say,  therefore, 
that  the  spinal   cord  and    brain  are  made    up    of   many 


Figure  222.  —  Nervous  System  of  Man. 


GROWTH  OF   THE   NERVOUS  SYSTEM 


211 


Figure  223.  —  Nerve  Cells. 


special    nerve    pathways    which   end    in   nerve  cells   thai 

interpret  stimuli. 

The  nerves  which  connect  the  central  nervous  system, 

that  is,  brain  and  spinal 

cord,  witli   all   parts  of 

the     body,     consist     of 

many  long  nerve  libers. 

Each  nerve  looks  like  a 

small  white  thread  and 

is  covered  with  a  thick, 

fatty  sheath  (medullary 

sheath).      In  the  living  animal,  this  fatty  sheath  is  white 

and   the  nerve  fibers  so  covered  are   found  to  occupy  a 

certain  part  of  the  spinal  cord  and 
brain.  Thus,  we  get  the  name  white 
substance.  Other  of  the  nerve  fibers 
and  cell  bodies  are  not  covered  with  a 
sheath  and  so  have  a  gray  appearance. 
Thus  we  have  the  term  gray  substance  in 
connection  witli  the  nervous  system. 

164.  Growth  of  the  Nervous  System.  — 
The  nervous  system  of  man,  like  all 
other  parts  of  the  body,  lias  a  definite 
beginning  and  grows  in  an  ordered 
manner.  Not  only  is  this  true  in  man, 
but  also  in  the  frog  and  fish.  The 
tissue  of  the  embryo,  which  is  to  grow 
into  brain  and  spinal  cord,  gradually 
changes  until  the  adult  parts  are  formed. 
During  this  early  period  of  growth,  the 
nerve  cells  send  out  processes  which 
become  nerve  fibers,  so  that  at  birth  the 

Figure  224. -Nerve    nervous   system   is  ready   to   go   to  work. 
Cells.  Indeed,  nearly  all  the  nerve  cells  which 


212 


THE  NERVOUS  SYSTEM  OF   MAN 


4 


..  ft*  <j* 

-  -  •* 


the  human  being  is  ever 
to  use  are  made  before 
birth.  These  cells  grad- 
ually become  more  active 
and  the  different  parts  of 
the  brain  work  more  per- 
fectly as  we  go  through 
the  periods  of  childhood, 
youth,  and  maturity. 
The  brain  becomes  a 
more  perfect  working 
organ  by  making  the 
brain  cells  do  their 
specific  work  over  and 
over  and  over,  until  each 
group  of  cells  can  be 
relied  upon  to  do  a 
definite  thing. 

165.  Reflex     Action.  — 

Reflex     action     is     the 

simplest  form  of  nervous  activity  in  man.     For  example, 

when  the  finger  is  placed  on  a  hot  stove  and  suddenly 


i 


Figure  225.  —  Micro-photograph  of 
Brain. 

The  nerve  cells  are  black. 


,sl<in 


ganglion 


'sensory 
fiber 


motor 
fiber 


% 

JVJJ 

rTMw* 

*  3 

>  °0   6* 

»   O  Oo 
>©  ©  * 

»°  ? .  *  ~  •  • 

%%° 

•V.-*.*:" 

motor  ce 

II 

muscle 

Figure  226.  —  Diagram  to  show  Reflex  Action. 

The  stimulus  comes  in  contact  with  the  skin  and  is  carried  to  the 
spinal  cord.  It  then  passes  to  the  motor  cells  which  carry  the  order 
to  the  muscle.  The  same  skin  stimulus  goes  to  several  other  parts  of 
the  spinal  cord. 


REFLEX   ACTION  213 

withdrawn  the  following  actions  take  place.  The  heal 
stimulus  affects  the  nerve  endings  in  the  finger  and  that 
stimulus  is  carried  to  the  spinal  cord.  If  this  were  all  that 
occurred,  the  finger  would  burn,  because  this  stimulus  and 
the  nerve  fibers  over  which  it  travels  have  no  control  over 
the  muscles.  The  removal  of  the  linger  calls  into  play  an- 
other set  of  nerve  cells, — the  cells  which  have  their  fibers 
ending  in  the  hand  and  arm.  All  of  these  changes  take 
place  involuntarily,  and  the  reaction  to  the  stimulus  is 
known  as  reflex  action.  Specific  names  are  used  in  de- 
scribing these  several  changes  ;  the  nerve  fibers  which 
connect  the  skin  with  the  spinal  cord  and  brain  are 
called  afferent  (affer-ent:  Latin,  ad,  to  ;  fero,  to  carry  ) 
fibers  because  the  stimulus  always  travels  toward  the 
brain. 

Their  function  is  sensory,  for  they  carry  the  stimulus  to 
the  brain.  The  fibers  which  connect  the  muscle  with  the 
brain  or  spinal  cord  are  the  efferent  (ef'fer-ent :  Latin, 
ex,  from  ;  fero,  to  carry)  fibers,  because  they  carry  their 
message  away  from  the  central  nervous  system.  Their 
function  is  motory.  In  the  special  instance  we  are  study- 
ing, the  heat  stimulus  causes  the  spinal  cord  to  send  a 
special  message  to  the  muscles  of  the  finger,  so  that  the 
latter  is  removed  from  the  stove. 

This  is  a  typical  illustration  of  the  simplest  way  in 
which  the  nervous  system  works,  but  in  most  reflex 
actions  there  are  other  results.  After  the  finger  has  been 
removed  from  the  hot  stove  by  reflex  action,  we  soon 
realize  that  the  skin  is  burned,  the  realization  oniim; 
through  the  smarting  sensation.  This  second  stimulus 
has  been  carried  to  the  brain,  and  we  are  now  conscious  of 
the  stove,  heat,  burn,  etc.  If  there  were  no  afferent  nerve 
fibers,  the  individual  could  not  experience  any  pain  when 
hurt. 


214  THE   NERVOUS  SYSTEM   OF   MAN 

The  afferent  and  efferent  nerves,  whether  in  reflex  or 
in  general  nervous  action,  never  vary  in  the  work  which 
they  do.  The  sensory  afferent  nerves  form  the  only  paths 
over  which  our  knowledge  of  the  outside  world  travels  to 
the  brain.  The  stimuli  which  cause  the  different  sensa- 
tions,  such  as  taste,  sight,  etc.,  have  their  individual  paths 
and  receiving  organs.  This  is  indicated  by  the  fact  that 
no  other  nerves  than  those  of  the  ear  are  ever  affected 
when  we  hear. 

Reflex  Action  in  the  Frog.  —  The  frog,  like  man,  is  able 
to  act  in  a  definite  way.  If  any  one  approaches  a  frog 
while  it  is  sitting  on  the  edge  of  a  pond,  it  jumps  into 
the  water,  stirs  up  the  mud,  and  then  returns  to  the  shal- 
low water  near  the  place  where  it  entered.  The  frog,  in 
this  case,  acts  as  if  it,  or  its  ancestors,  had  learned  that 
this  is  the  best  way  to  escape  enemies.  While  this  series 
of  acts  is  called  a  habit,  it  is  really  a  series  of  reflex  acts 
which  are  similar  to  the  reflex  action  described  for  man, 
and  require  the  same  nerve  structures. 

Reflex  Action  in  the  Earthworm.  —  If  a  light  is  flashed 
on  an  earthworm  at  night,  the  worm  will  quickly  with- 
draw to  its  burrow,  before  it  can  be  seized.  The  earth- 
worm has  no  eyes,  but  it  is  able  to  respond  to  light  and 
can  tell  the  difference  between  night  and  day.  It  is 
believed  that  special  nerve  cells  in  the  skin,  which  are 
connected  with  the  nerve  ganglia,  help  the  earthworm  to 
become  aware  of  the  light  stimulus. 

Reflex  Action  in  Hydra.  —  Hydra  is  a  minute  water 
animal  which  has  no  definite  nervous  system,  but  only 
a  few  nerve  cells  scattered  through  the  body.  As  the 
hydra  waves  its  arms  about  in  the  water,  there  seems  to 
be  no  purpose  in  its  motions.  But  if  a  water  flea  swims 
against  one  of  the  tentacles,  a  part  or  all  of  the  tentacles 
at  once  begin  to  carry  the  flea  to  the  mouth  of  the  hydra. 


SENSE  ORGANS  215 

The  hydra,  then,  without  a  definite  nervous  system,  ran 
carry  out  a  definite  reflex  action. 

Reflex  action  is  similar  in  all  animals.  In  all  of  these 
illustrations,  it  is  necessary  for  the  stimulus  to  be  received 
by  an  afferent  nerve,  or  some  structure  which  can  do  the 
same  work,  and  for  the  stimulus  to  be  transformed  into  a 
series  of  purpose-like  movements. 

166.  Sense  Organs. — All  of  the  higher  animals  have 
eyes,  ears,  a  nose,  and  a  tongue.  Each  of  these  organs 
contains  nerves  specialized  to  respond  to  a  certain  definite 
kind  of  stimulus.  The  result  of  this  specialization  is  that 
not  only  are  these  special  sense  organs  complex:  in  struc- 
ture, but  also  the  region  of  the  brain  which  receives  their 
messages.  The  ear  nerve  responds  to  a  stimulus  of 
air-waves  of  a  certain  length,  and  we  say  we  hear  a 
sound.  The  eye  nerve  is  stimulated  only  by  light. 
Each  nerve  and  the  brain  cells  to  which  it  sends  its 
messages  have  become  so  specialized  that  practically 
only  one  kind  of  reaction  takes  place.  For  example, 
all  stimuli  acting  upon  the  eye  nerves  are  interpreted 
as  light. 

The  skin  is  a  simpler  sense  organ  than  the  eye  or  ear. 
and  tells  us  of  pain  and  touch  and  the  difference  between 
heat  and  cold. 

The  Eyes.  — The  eyes  of  all  vertebrates  have  the  parts 
arranged  in  a  similar  manner.  The  eyeball  is  roundish 
and  is  located  in  the  eye  sockets  of  the  skull,  which  are 
termed  orbits.  There  is  an  upper  and  a  lower  eyelid,  and 
the  remains  of  a  third  eyelid  in  the  corner  next  to  the 
nose.  The  front  of  the  eve  is  covered  by  a  transparent 
membrane,  the  cornea  (kor'ne-a);  and  the  rest  of  the 
eye  is  surrounded  by  a  tough  membrane,  the  Bclerotic 
coat,  or  the  white  of  the  eye.  Within  the  combined 
covering  of  the  cornea  and  sclera  are  a  number  of  struc- 


216 


THE   NERVOUS  SYSTEM   OF   MAN 


tures  which  take  part  in  receiving  and  transmitting  the 
rays  of  light  to  the  brain. 

A  cross  section  of  the  eye  shows  two  more  membranes 
in  close  relation  to  the  sclerotic  coat  (Figure  227).     The 

membrane  in  direct  con- 
tact on  the  inside  with 
the  sclerotic  layer  is  the 
choroid  (ko'roid).  The 
choroid  coat  is  filled 
with  blood  vessels  and 
pigment.  Through  this 
layer  the  food  in  the 
blood  is  distributed  to 
the  eye.  The  third 
layer  or  coat  is  the 
retina,  which  is  com- 
posed of  nerve  cells  and 
which  is  nearly  trans- 
parent. 
The  cornea  and  these  three  layers  inclose  two  chambers 
which  are  separated  by  the  lens  (Figure  227).  In  front  of 
the  lens  a  curtain-like  membrane,  the  iris,  partly  covers 
the  lens,  except  for  a  round  opening  in  the  center  which  is 
called  the  pupil.  The  color  of  the  eye,  gray,  black,  blue,  or 
brown,  is  due  to  the  presence  of  pigment  in  the  iris.  The 
small  front  chamber  is  filled  with  a  transparent  fluid  which 
is  composed  principally  of  water  and  is  known  as  the 
aqueous  (a/kwe-us)  humor.  The  large  back  chamber  is 
filled  with  a  thin,  transparent,  jellylike  fluid,  the  vitreous 
(vit're-us)  humor. 

In  order  that  wTe  may  see  any  object,  a  pencil  in  our 
hand,  for  example,  two  general  conditions  must  be  present. 
The  picture  (image)  of  the  pencil  must  be  placed  on  the 
retina,  and  this  picture  must  be  carried  to  the  brain  by 


Figure  227.  —  Section  of  Eye. 

C,  cornea  ;  C',  choroid  layer  ;  /,  iris  ; 
I.  C,  inner  chamber  ;  0.  C,  outer  cham- 
ber ;  L,  lens  ;  0.  N,  optic  nerve ; 
R,  retina  ;    S,  sclerotic  coat. 


e 

Figure  228.  —  How  we  see  the  Pencil. 


SENSE  ORGANS  217 

the  eye  (optic)  nerve.      When  these  two  conditions  bake 
place,  we  see. 

As  we  have  learned,  the  stimulus  for  the  eye  is  always 
light.  In  physics  we  learn  that  the  rays  of  light  brave]  in 
straight  lines.  This  fact  explains  why  we  cannot 
round  a  corner.  When  the  rays  of  light  are  made  to  pass 
through  a  glass  lens,  the  rays  which  pass  through  the  thin 
edges  of  the  lens  are  bent  and  do  not  travel  to  the  same  place 
they  would  have  reached  had  they  not  passed  through  the 
lens.  In  the  same  way  light  rays  from  an  object  pass 
through  the  lens  in  our 
eyes  and  are  bent.  This 
results  in  the  image  of 
the  object,  the  pencil  in 
this  instance,  being  in- 
verted on  the  retina. 
The  light  rays  of  the  pencil  stimulate  the  nerve  cells  in 
the  retina,  and  this  stimulus,  after  being  carried  to  the 
brain,  is  interpreted  to  us  as  a  pencil,  though  we  do  not 
know  how  stimuli  travel  on  nerves.  The  inverted  image 
of  the  picture  on  the  retina  is  made  to  look  natural  to  us 
because  we  are  used  to  seeing  everything  in  inverted  imag 

Care  of  the  Eyes.  —  The  eyes  are  our  most  precious 
sense  organs,  and  as  such  they  should  receive  the  best  of 
care.  Certain  imperfections  in  the  lens  or  other  parts  of 
the  eye  can  be  helped  by  the  use  of  glasses.  If  your  «\  ea 
annoy  you,  or  if  you  cannot  see  objects  as  clearly  as  your 
schoolmates,  have  a  competent  oculist  examine  and  treat 
them. 

The  Ear.  — The  ear  is  a  sense  organ  for  the  reception 
of  the  stimuli  which  we  interpret  as  sounds.  The  ear  of 
man  consists  of  the  outer,  middle,  and  inner  ear.  The 
first  two  carry  the  stimuli  to  the  third,  where  the}'  are 
received  by  nerve  cells  and  carried  to  the  brain. 


218 


THE   NERVOUS  SYSTEM   OF   MAN 


The  diagram  of  the  ear  (Figure  229)  shows  the  several 
parts  and  their  relations.  The  outer  ear  leads  to  the  tym- 
panic (tim-pan'ik)  cavity  ;  the  middle  ear  is  in  commu- 
nication with  the  mouth,  and  the  complex  inner  ear  is 
partly  shown.  There  is  a  group  of  small  bones  in  the 
middle  ear  which  conduct  the  sound  vibrations  to  the 
delicate  inner  ear.     The  internal  ear  receives  the  various 

sound  waves,  and  transmits 
them  to  the  brain,  where  they 
are  explained  as  sounds.1 

Hearing.  —  Sound  waves  strike 
the  ear  drum  (tympanic  mem- 
brane), which  in  turn  causes  the 
small  bones  in  the  middle  ear  to 
vibrate.  The  bones  cause  the 
water  in  the  internal  ear  to 
move,  thus  stimulating  the 
nerves  of  hearing. 
The  pressure  of  air  on  each  side  of  the  ear  drum  is  nor- 
mally the  same.  This  is  due  to  the  entrance  into  the  mid- 
dle ear  of  air  from  the  mouth,  through  the  eustachian 
tube  (see  page  166).  This  tube  is  a  trifle  more  than 
an  inch  long.  When  it  becomes  closed,  partial  deafness 
results. 

Defects  in  hearing  may  be  caused  by  blows  upon  the 
ears,  by  the  accumulation  of  wax  in  the  ears,  and  by  sore 
throat.  When  there  is  a  continued  ringing  or  hissing 
sound  in  the  ears,  consult  a  doctor  at  once. 

167.  Brain  Efficiency.  —  While  the  efficiency  of  the  brain 
depends  upon  mental  training,  in  order  properly  to  exer- 
cise the  many  functions  of  this  organ  at  least  three  things 


Figure  229.  —  Plan  of  Ear. 

0.  E,  outer  ear  ;  M.  E,  middle 
ear ;  /.  E,  inner  ear ;  Eu,  eu- 
stachian tube. 


1  When  certain  parts  of  the  ear  (semicircular  canals)  are  injured,  one  has 
difficulty  in  standing  or  in  walking  erect.  This  is  because  the  inner  ear 
serves  both  as  a  hearing  and  a  balancing  organ. 


BRAIN   EFFICIENCY 


219 


SKILL  AND    ENDURANCE    IMPAIRED 

BY    DRINK 

Tests  in  Target-Shooting  in  Swedish  Army 

I.   SKILLED    TESTS 

Thirty  shots  fired  in  quick  succession 

Non-Drinking  Days:  Average  24  hits  oat 
of80  Bhots 

Drinking  Days:   Average  8  bits  onl   of 

:5n   Shots 

■ 

Alcohol  taken  equal  to  amount  in  P.j  to  2 
pints  of  5  per  cent  beer,  •_'(»  to  80  minutes 
before  shooting,  and  an  equal  amount  the 
night  before 

II.    ENDURANCE    TESTS 
Non-Drinking  Days:  860  Bhots  fired  be- 
fore exhaustion 

Drinking  Days:  2TS  shot-  fired  before  i  I 
haustion 


Alcohol  taken  3o  minutes  before  tesl  vras 
amount  contained  in  about  ll/4  pints  of 
4  per  cent  beer 


are  necessary:  good  food,  sufficient  sleep,  and  abstinence 
from  alcohol  and  tobacco.     We  have  already  discussed  the 

question  of  food  (page  169). 

The  amount  of  sleep  which  grown  people  need  depends 
in  part  upon  the  kind  and  amount  of  work  they  do.  But 
all  young  people  require  a  large  amount  of  sleep.  Chil- 
dren from  seven  to  ten  years  of  age  need  at  least  twelve 
hours  of  sleep  every  night, 
while  youths  of  high  school 
age  need  at  least  nine  hours, 
and  ten  would  be  better. 

At  a  baseball  game,  you 
have  noticed  a  boy  catch  a 
"  fly  "  when  it  looked  like  a 
"  home  run,"  or  how  enthu- 
siastic the  crowd  became 
when  the  pitcher  struck  out 
the  last  man  with  the  bases 
full.  The  nervous  system 
of  both  players  was  efficient 
in  a  critical  test. 

We  all  ride  on  the  street 
cars  or  railroads,  but  do  you 
know  that  most  of  the  men 
who  run  the  street  cars  and 
trains  have  to  pass  an  ex- 
amination to  determine  whether  they  can  be  trusted  to  do 
their  work  properly  and  well  ;  i.e.,  whether  their  nervous 
systems  will  stand  the  test?  Among  the  questions  which 
their  prospective  employers  are  sure  to  ask  is.  M  Do  you 
use  alcoholic  drinks  ?  " 

In  order  to  judge  the  success  of  a  piece  of  work  we  must 
consider  the  quality  and  speed  with  which  it  is  done. 
Kraepelin  made   the  following  experiment,  the  results  of 


Figure  230. 


220  THE   NERVOUS   SYSTEM   OF   MAN 

which  show  that  both  these  elements  in  mental  work  are 
influenced  by  the  use  of  alcohol. 

Several  men  who  were  allowed  to  drink  no  alcohol  util- 
ized half  an  hour  daily  for  six  days  in  adding  figures. 
Their  ability  to  add  increased  each  day.  On  the  seventh 
day  the  work  was  begun  under  the  influence  of  alcohol. 
In  spite  of  the  skill  gained  in  the  previous  practice,  their 
accuracy  did  not  increase,  but  on  the  contrary  began  to  de- 
crease rapidly.  On  the  nineteenth  day  the  use  of  alcohol 
was  stopped,  and  immediately  an  improvement  in  the  work 
manifested  itself  ;  but  on  the  twenty-sixth  day,  when  the 
use  of  alcohol  was  resumed,  a  decided  decrease  in  the 
power  of  adding  manifested  itself.1 

It  is  difficult  to  estimate  how  efficient  each  of  us  may 
become  in  our  life  work,  but  one  thing  is  certain,  that  if 
we  use  alcohol,  we  shall  lose  that  perfect  control  over  our 
nervous  systems,  which  enabled  the  two  players  to  be  so 
efficient  in  the  ball  game.  It  is  also  equally  certain  that 
if  we  use  alcohol,  we  shall  find  fewer  men  willing  to  em- 
ploy ns  in  places  of  responsibility,  not  only  because  of  our 


1  Schiller  was  wont  to  say,  "  Wine  never  invents  anything,"  and  Helmholtz, 
one  of  the  greatest  observers  and  thinkers  of  the  nineteenth  century,  noted  in 
himself  the  effect  of  alcohol  in  interfering  with  the  highest  powers  of  thought 
and  conception.  At  the  celebration  of  his  seventieth  birthday  in  Berlin,  when 
the  courts  of  Europe  and  the  whole  scientific  world  joined  to  confer  numerous 
honors  upon  Helmholtz,  he  described  in  the  course  of  a  speech  the  coudition 
under  which  his  highest  scientific  thoughts  had  matured  and  come  to  fruition. 
He  said : 

"  Frequently  they  slyly  enter  the  mind  without  one's  immediately  attach- 
ing any  importance  to  them  ;  later  some  very  simple  accident  or  circumstance 
may  be  sufficient  to  reveal  to  us,  when  and  under  what  circumstances  they 
arose,  or  they  may  be  present  without  our  even  knowing  from  whence  they 
came.  At  other  times  they  come  to  us  suddenly,  without  any  exertion  what- 
ever, just  as  an  inspiration.  As  far  as  my  experience  is  concerned,  they 
never  came  to  a  wearied  brain,  or  at  the  writing  desk.  They  were  especially 
inclined  to  appear  to  me  while  indulging  in  a  quiet  walk  in  the  sunshine  or 
over  the  forest-clad  mountains,  but  the  smallest  quantity  of  alcohol  seemed  to 
scare  them  away." 


ALCOHOL,   A    NARCOTIC 


22 1 


DRINK  impaired  SCHOLARSHIP 

A   Comparison   of  Abstaining   and 
Drinking  School  Children  in  Vienna 

Investigation  concerned  ">sv»  pnpili  in  ll  classes 
Drinks  used  included  Wine.  Beer  and  Knm  in  tea 


mental   inefficiency,    bnt    also   because    of   our   unreliable 
judgment. 

Alcohol  Shortens  Life.  — At  least  nineteen  of  the  great 
American  life  insurance  companies  do  not  consider  thai  ;i 
man  who  uses  alcohol  is  a  good  risk,  because  be  does  not 
live  so  long  as  the  man  who  abstains.  The  statistics  of 
one  insurance  company,  which  cover  the  period  1*H4- 
1909,  show  that  during  that 
period  79.7  %  of  their  risks 
who  were  moderate  drinkers 
died  ;  while  but  52.2  °f0  of 
the  abstainers  died.  In  the 
case  of  a  second  company, 
during  the  period  1886-1909, 
93%  of  the  drinkers  and  only 
70  %  of  the  abstainers  died. 

168.  Alcohol,  a  Narcotic. — 
Before  studying  this  subject 
further,  we  must  understand 
the  meaning"  of  the  terms 
poison,  anesthetic  (an-es- 
thet'ik),  and  narcotic.  A 
poison  is  a  substance  which 
when  taken  into  the  body 
tends  to  cause  death.  Aco- 
nite, opium,  carbolic  acid, 
and  mercury  are  all  poisons,  and  when  taken  in  sufficient 
quantities  cause  death. 

An  anesthetic  is  a  substance  like  ether  or  chloroform, 
which  when  breathed  into  the  lungs  causes  a  temporary 
loss  of  sensation.  However,  unless  anesthetics  are  admin- 
istered properly,  they  may  cause  death. 

A  narcotic  is  a  substance  which  causes  dullness  or 
stupor,  and  even  a  temporal}'   relief   from  pain. 


=  Highest         W.  Fair         nans  Poorest 
134  Abstaining  Children 

42%  49 

y//Mw/W/Z$Z>/..        J 
164  Who  Drank  Occasionally 

34%  57'  ; 

■ 


219  Who  Drank  Once  a  Day 


29' 


71  Who  Drank  Twice  a  l):i\ 
25%  58  18', 

Highest  Scholarship  Decreased,  Peered  In- 
creased, as  the  I  se  of  Lleohol  »;is  Increased 

[nveatigation  bj  E.  Bajrr,  School  Din 


Figure  231 


222 


THE   NERVOUS  SYSTEM   OF   MAN 


Assaults  and  Drink 

1,115  Assaults  in  Heidelberg,  Ger.,  1900-1904 
66.5';     Committed  in  Saloons 


8.8% 
7.8% 

7.7% 
9.2% 


Committed  in  Street 


Committed  in  Workshop 


Committed  at  Home 


To  understand  how  alcohol  comes  to  be  classed  as  a 
narcotic,  it  is  necessary  to  learn  about  a  substance  called 
lipoid  (Greek,  lipos,  fat  ;   eikos,  like). 

"  Within  recent  years  a  new  sort  of  body  substance  has 
been  discovered,  and  has  been  elevated  to  first-rate  im- 
portance. This  new  class  is  termed  'lipoid.'  Its  impor- 
tance is  immense.    It  is  quite  as  important  in  the  body  as  the 

nitrogenous  or  albuminous 
material  which  is  present  in 
every  living  tissue.  It  is 
very  like  fat  in  many  re- 
spects, but  in  other  respects 
it  is  different.  It  contains 
nitrogen,  which  fats  do  not; 
it  contains  phosphorus, 
which  fats  do  not;  again  it 
mixes  with  water,  which,  as 
is  well  known,  fats  do  not. 
It  has  certain  remarkable 
properties,  in  that  it  can 
make  certain  bodies  soluble 
which  are  otherwise  not 
soluble. 

"  The  walls  of  practically 
every  living  cell  in  the 
whole  body  are  made 
chiefly  of  lipoid,  and  it  is  found  that  there  are  strands 
of  this  material  running  through  and  through  the  sub- 
stance of  every  cell.  In  fact,  there  is  no  region  of  any 
cell  in  any  part  of  the  body  that  is  without  this  material. 
"  Perhaps  the  largest  accumulation  of  lipoid  is  that  in 
the  nervous  system.  There  is  far  more  lipoid  in  the 
brain  than  in  any  other  tissue.  If  you  examine  a  nerve, 
or  what  physiologists  call  a  nerve  trunk,  you  will  find 


Place  Unknown 

Man;  assaults  committed  outside 
the  saloon  were  also  due  to  drink 


The  Sober  Man  Thinks  Before  He  Acts 

Alcohol  Makes  a  Man  Act  Before  He  Thinks 

It  causes  irritability  ;  weakens  the 

judgment  and  self-control  needed 

to  hold  irritability  in  check 

"  Our  statistics  (from  the  United  States) 
point  to  the  conclusion  that  intemperance 
is  the  one  moxt  prolific  source  of  the 
criminal  co)u/itio}i.'n — Co.m.m.  of  Fifty. 


Figure  232. 


ALCOHOL,   A   NARCOTIC 


223 


that  this  nerve  is  composed  of  many  thousands  of  nerve 
fibers,  and  each  nerve  fiber  that  conveys  messages  into  or 
out  of  the  brain  is  invested  with  an  insulation  jacket  (sim- 
ilar to  the  insulation  covering  an  electric  wire)  of  Lipoid 
and  thus  the  stimuli  are  prevented  from  scattering. 

"It  may  be  asked,  'What  has  all  this  to  do  with 
alcohol?'  The  connection  is  an  important  one,  for  only  a 
few  years  ago  two  physiological  investigators,  —  one  with 
the  English  name  of  Overton,  and  the  other  with  the  dis- 
tinctly German  name  of  Hans  Meyer,  —  without  knowledge 
of  each  other's  work,  discovered  the  principle  that  any 
substance  that  dissolved  lipoid,  or,  what  is  the  same  thin.;, 
is  dissolved  in  lipoid,  is  an  anesthetic.  Chloroform,  ether, 
and  all  of  these  agents  which  are  used  in  modern  surgery 
to  produce  unconsciousness  are  dissolvers  of  lipoid. 

"Besides  acting  as  anesthetics  such  substances  act  as 
poisons  to  every  living  thing  in  the  body  as  well.  The 
brain,  owing  to  its  high 


tt'iciency  Onter 

Wora  Centers 

Balancing  Centers 
BreathingCeM.r 

Hrtii  Ccnler 


percentage  of  lipoid,  is 
more  sensitive  to  the 
action  of  chloroform  than 
other  organs  of  the  body. 

"  When  chemists  and 
physiologists  found  that 
alcohol  is  soluble  in 
lipoid,  it  enabled  them 
to  rank  it  as  a  narcotic 
poison,  and  it  is  now  so 
classed.     This  statement 

is  altogether   irrespective  of   the  effects  it   will   produce 
on  an  animal." — Osborne. 

The  question  of  brain  efficiency  is  further  illustrated  by 
Figure  233.  Long  before  birth  the  heart  in  the  embryo 
begins  to  beat  and  is   under  the   control   of   the   nervous 


Nerve  to  Heart 


Figure  233.  —  Brain  Control. 


224 


THE  NERVOUS  SYSTEM  OF  MAN 


Abstainers'  Advantace 

In  a  Championship  Walking  Match 

MATCH  HELD  AT  KIEL,  GERMANY,  1908 

59    Non-Abstainers,   24  Abstainers   Entered 
Contestants  Entering  Match 

Kon- Abstainers  71%  Abstainers  29% 


Percentage  of  Prizes  Won 

By  \nn- Abstainers  40%      By  Abstainers  60% 


Of  First  25  to  Reach  Coal 


system.  The  part  of  the  brain  which  superintends  the 
heart  is  located  in  the  medulla,  where  a  special  cluster  of 
cells  sends  out  nerve  fibers  which  enter  the  heart  nerve. 
These  nerve  cells  are  called  the  heart  center. 

The  next  nerve  center  to  begin  work  is  the  breathing 
center,  located  close  to  the  heart  center,  which  controls  the 
breathing.     This  does  not  become  active  until  after  birth. 
About  a  year  after  birth,  several  more  nerve  centers  be- 
come active  in  the  child's  brain.     These  are  the  ones  which 

help  him  to  walk.  The  cere- 
bellum contains  nerve  cen- 
ters which  play  an  important 
part  in  walking  and  in  learn- 
ing to  balance.  The  muscles 
which  move  the  arms  and 
legs  are  regulated  by  nerve 
centers  in  the  cerebrum. 

Soon  after  the  child  learns 
to  walk,  he  begins  to  talk 
and  learn  words.  The  sev- 
eral nerve  centers  which  now 
become  active  are  all  located 
in  the  cerebrum.  These  are 
the  nerve  cells  which  are 
necessary  in  speaking,  hear- 
ing, reading,  and  writing 
words. 

After  fifteen  years  of  age 
the  brain  goes  through  important  structural  changes  and 
the  young  person  begins  to  do  difficult  tasks  well.  It  is 
difficult  to  locate  the  exact  spots  in  the  cerebrum  where  the 
nerve  centers  are  that  now  become  active,  for  they  are 
widely  distributed.  These  nerve  centers  may  be  called 
the  efficiency  centers  and  they  are  the  last  to  develop.     But 


Failed  to  Reach  Coal 

94%  were  Non- Abstainers  6%  were  Abstainers 


Abstainers  won  1st,  2d,  3d,  4th,  8th  Places. 
Xon-Abstainers,  5th,  0th,  Tth  Places. 


Figure  234. 


STRUCTURAL   CHANGES  DUE   TO  ALCOHOL      22.") 

as  they  become  active,  every  one  becomes  skillful  along 
some  particular  line,  although  many  years  of  training  are 
necessary  before  the  maximum  of  efficiency  is  reached. 

The  efficiency  centers  which  are  the  last  to  become  ac- 
tive and  which  require  so  much  energy  to  train  properly 
are  the  first  to  be  affected  by  alcohol. 

169-  Structural  Changes  Due  to  Alcohol. —  Definite  changes 
are  found  in  the  protoplasm  of  nerve  cells  after  the  use  of 
alcohol.  These  consist  in  a  shrinking  of  the  nucleus,  the 
loss  of  the  spindle-shaped  (Nissl)  bodies  (Figure  224), 
the  swelling  of  the  cell,  and  the  presence  of  vacuoles 
in  the  cytoplasm.  It  is  also  probable  that  some  of  the 
nerve  cells  are  actually  destroyed.  These  physical 
changes  explain  why  the  results  are  so  great  and  why 
complete  recovery  of  mental  efficiency  in  the  drunkard  is 
so  doubtful.  The  modern  point  of  view  and  the  one 
which  is  becoming  firmly  established  in  the  treatment  of 
drunkards  by  physicians  is  that  alcoholism  is  a  disease. 
Many  of  the  authorities  on  alcoholism  are  urging  that 
drunkards  should  be  cared  for  just  as  we  care  for  people 
sick  with  diphtheria  or  tuberculosis. 

Anything  which  can  destroy  all  of  the  higher  and  finer 
emotions,  take  away  ambition,  destroy  shame,  modesty, 
pride  in  personal  appearance,  render  one  especially  liable 
to  common  diseases,  or  lead  unerringly  to  insanity  is 
to  be  avoided  by  those  who  are  strong  enough  to  resist, 
and  should  be  made  inaccessible  to  those  who  are  weak 
and  ignorant.       And  alcohol  has  all  these  effects  on  man.1 

1  Alcohol  tills  our  state  hospitals  for  the  insane.  Insanity  is  a  disorder  <>f 
the  mind  due  to  various  causes.  The  one  cause  which  produces  thegreatesl 
number  of  cases  is  the  intemperate  use  of  narcotics,  «>f  which  ah-,, In, I  in  it- 
various  forms  is  the  most  common.  No  less  than  twenty-sis  per  cenl  .>!'  the 
inmates  of  our  state  institutions  for  the  insane  have  become  deranged  :i-  the 
result  of  intemperance. 

There  can  he  no  doubt  that  some  persons  air  more  Busceptible  t"  the  in- 
fluence of  alcohol  than  others.    They  become  easily  intoxicated  and  readily 


226  THE  NERVOUS  SYSTEM  OF   MAN 

170.    Tobacco.  — "  Training   starts   to-morrow,    no    more 
smoking,"  is  part  of   the  athletic  coach's   orders  at   the 


succumb  to  disease.  Others  appear  to  resist  the  daily  use  of  moderate  quan- 
tities  for  a  long  time  and,  to  the  ordinary  observer,  seem  to  be  in  good  health. 
Slow  changes,  not  easily  detected,  however,  are  taking  place  in  the  blood 
vessels,  brain,  stomach,  and  other  organs,  which  will  in  time  become  apparent 
in  serious  ill  health.  Tbese  changes  are  organic,  that  is,  the  structure  of  the 
organs  is  changed,  and  even  if  the  alcoholic  drinks  be  then  wholly  aban- 
doned, the  organs  will  not  return  to  a  healthy  condition  —  though  further 
damage  may  be  averted  by  this  course. 

"  Influence  of  Alcohol  on  the  Development  of  the  Brain.  The  brain  and 
spinal  cord  do  not  reach  complete  development  until  the  age  of  twenty-four  or 
twenty-five  yeai'S.  During  that  time  it  is  of  particular  importance  that  they 
be  well  nourished,  supplied  with  an  abundance  of  pure  oxygen  by  the  blood, 
and  that  all  substances  likely  to  injure  their  delicate  structure  be  excluded. 
One  would  not  expect  to  produce  a  fine  flower  from  a  plant  which  had  been 
neglected  or  abused.  It  is  well  known  to  the  florists  who  raise  wonderfully 
beautiful  chrysanthemums  that  perfect  blooms  cannot  be  produced  on 
plants  which  have  suffered  even  a  slight  injury  from  drought  or  other  cause. 
No  amount  of  care  subsequently  bestowed  will  result  in  anything  more  than 
a  mediocre  blossom.  The  human  brain  is  in  structure  and  function  the  most 
wonderful  product  of  nature.  It  needs  even  more  than  a  plant  to  be  protected 
from  harmful  influences,  in  order  that  its  millions  of  tiny  cells  and  fibers  may 
be  properly  built  up  day  by  day  as  the  brain  and  body  grow.  Alcohol  will 
produce  in  a  mature  man  such  a  disturbance  of  the  functions  of  the  brain  and 
spinal  cord  that  he  will  be  for  a  time  unable  to  walk  steadily  or  to  speak 
distinctly.  It  would  be  idle  to  expect  the  immature  nervous  system  of  a  boy 
or  girl  to  develop  properly  if  exposed,  even  occasionally,  to  the  influence  of 
such  a  powerful  poison.  The  bad  effect  is  twofold.  Healthy  growth  is  inter- 
fered with,  and  the  habit  of  craving  a  stimulant  is  more  easily  acquired  than 
in  an  adult.  The  same  is  true  of  the  tobacco  habit ;  it  is  seldom  contracted 
except  in  early  life.  It  has  been  found  among  those  who  became  insane  from 
the  use  of  alcohol,  that  a  very  large  majority  began  its  use  when  less  than 
twenty  years  of  age. 

"  Persons  most  easily  harmed  by  alcohol  are  those  who  are  most  suscepti- 
ble to  it.  One  who  becomes  intoxicated  by  a  relatively  small  quantity  of 
alcohol,  who  when  under  its  influence  shows  a  change  of  disposition  by  speech 
or  behavior  different  from  what  is  normal  to  him,  or  who  after  its  effects  have 
passed  away  cannot  remember  what  he  did  or  said  while  under  its  influence, 
has  this  susceptibility.  Its  continued  use  by  such  a  person  will  inevitably 
lead  to  the  most  serious  results.  The  same  is  true  of  all  women.  Women 
and  girls  are  more  susceptible  to  alcohol  than  the  opposite  sex,  and  show,  at 
an  early  period,  that  peculiar  blunting  of  the  intellectual  and  moral  faculties 
which  make  their  appearance  at  a  later  period  in  men."  —  R.  H.  Hutchings, 
M.D.,  Superintendent,  St.  Lawrence  New  York  State  Hospital  for  the  Insane. 


HOW   THE  SMOKER'S   HEART  IS   AFFECTED       227 

beginning  of  eacli  season.  lie  knows  that  the  boy  who 
smokes  cannot  reach  his  highest  efficiency  <>r  be  relied 
upon  at  critical  times  in  the  contest.  He  would  rather 
have  boys  who  do  not  smoke,  because  they  an-  stronger, 
larger,  and  steadier  than  those  who  smoke.  The  cigarette 
habit  has  spread  until  it  threatens  the  health  of  thousands 
of  boys  of  America  to-day.  How  is  it  known  that  their 
health  is  not  so  good  ?  The  charts  on  "smoker's  heart' 
prove  this  point. 

171.  How  the  Smoker's  Heart  is  Affected.  —  The  follow- 
ing illustrations  on  the  rate  of  the  heart  beat  and  the 
strength  of  the  pulse,  by  W.  A.  McKeever,  show  what 
really  happens  when  we  smoke.  There  is  much  in  these 
illustrations  to  warrant  the  conclusion  that  the  heart  of 
the  habitual  cigarette  smoker  is  weak  and  feeble,  except 
for  the  few  minutes  during  which  he  is  indulging  the 
habit,  and  that  the  pulsations  at  this  time  are  unduly 
excited.  Figure  235  shows  three  records  of  a  young  man 
nineteen  years  old  who  began  smoking  cigarettes  at  the 
age  of  fifteen  and  who  inhaled  the  fumes.  The  three 
records  were  taken  without  removing  or  readjusting  the 
instrument,  as  follows :  No.  I,  immediately  before  smok- 
ing ;  No.  II,  during  the  indulgence  of  the  habit,  and  No. 
Ill,  fifteen  minutes  later,  after  the  effect  of  the  narcotic 
had  become  apparent.  Now,  by  reference  to  Figure  -3»>, 
No.  Ill,  we  may  observe  how  this  young  man's  heart 
should  record  itself,  for  the  latter  is  the  tracing  of  the 
heart  pulsations  of  a  normal  young  man  of  the  same  age 
and  temperament.  Nos.  IV  to  VI  (  Figure  -'■).'>)  are  repre- 
sentative of  another  inhaler  twenty  years  old,  who  began 
the  practice  at  thirteen.      He  now  uses  a  strong  pipe. 

In  Figure  236,  Nos.  I  and  II,  taken  respectively  before 
and  after  smoking,  are  tracings  of  a  sensitive  youth  of  eigh- 
teen who  has  been  smoking  only  two  years.      Observe  the 


228 


THE  NERVOUS  SYSTEM  OF   MAN 


Figure  235. 


skip  of  his  heart  beat  at  x  and  the  corresponding  partial  skip 
under  the  stimulus  of  smoking  in  No.  II.     No.  Ill  (Figure 

236),  as  mentioned  above, 


is  a  tracing  of  a  strong 
healthy  heart  of  a  young 
man  of  somewhat  excit- 
able temperament.  No. 
IV  represents  the  phleg- 
matic temperament,  that 
is,  a  person  who  is  cool 
and  calculating.  No.  V 
is  the  heart  tracing  of  a 
strong  and  healthy 
young  woman. 

In  Figure  237,  Nos.  I 
and  II  are  the  pulse  records  of  a  man  of  splendid  physique, 
thirty-six  years  old  and  weighing  230  pounds.  No.  I 
was  taken  before  and  No.  II  after  smoking  a  cigar.  He 
does  not  inhale.  His  pulse  responded  readily  to  the 
stimulus,  but  as  the  first  tracing  indicates  he  does  not 
seem  to  suffer  from  any 
heart  prostrations  be- 
tween indulgences. 
No.  Ill  is  the  record  of 
a  person  whose  vitality 
is  temporarily  low  from 
nervous  fatigue.  No. 
IV  is  the  record  of  a 
young  woman  who  was 
on  the  verge  of  nervous 
prostration.  No.  V  is 
representative  of  a  heart 

weakened  by  long  indulgence  in  the  smoking  habit.     The 
young  man  in  question  began   early  and   continued  the 


Figure  236. 


SMOKING  AND  SCHOLARSHIP 


•2-l\) 


practice  till  his  physician  convinced  him  of  the  extreme 
danger  threatening  his  life.  The  pulse  wave  is  nearly 
normal  in  length,  but  is  entirely  too  weak.  Under  such 
conditions  of  heart  a  man  is  capable  of  Little  courage  or 


aggressiveness. 


Figure  237. 


"From  the  foregoing  evidence  we  are  led  to  the  con- 
clusion that  in  the  case  of  boys  and  youths  cigarette 
smoking  is  very  dele- 
terious to  the  physical 
and  mental  well-being. 
Moreover  my  investiga- 
tions indicate  that  it 
makes  very  little  dif- 
ference in  the  effects 
whether  the  victim  uses 
pipe  or  cigarettes,  pro- 
vided he  inhales  the 
fumes  ;  and  with  few 
exceptions     the     young 

smokers  are  inhalers.  The  ordinary  case  exhibits  about 
the  following  type  of  conduct  :  (1)  While  the  craving  is 
at  its  height  the  victim  manifests  much  uneasiness  and 
often  much  excitation.  (2)  During  the  indulgence  the 
cheek  is  alternately  flushed  and  blanched,  the  respiration 
considerably  increased  and  the  hands  tremble.  (3)  About 
twenty  minutes  after  smoking  the  muscles  become  relaxed. 
the  respiration  slow  and  shallow,  the  skin  on  the  face  dry 
and  sallow  and  there  is  an  apparent  feeling  of  unconcern 
about  everything."  —  W.  A.  McKeeveb. 

172.  Smoking  and  Scholarship.  —  Several  thousand  boys 
have  been  studied  and  classified  according  to  acre  and 
whether  they  were  smokers  or  non-smokers.  In  all  cases 
the  non-smokers  had  a  higher  average  grade  of  scholar- 
ship.    The  experience  of  city  superintendents  and  prin- 


230  THE  NERVOUS  SYSTEM  OF  MAN 

cipals  is  that  they  can  usually  tell  a  cigarette  boy  by  his 
general  attitude,  poor  scholarship,  and  disregard  of  per- 
sonal appearance. 

When  cigarettes  are  burned,  three  distinct  poisons  are 
produced,  which  cause  serious  effects  on  the  boys  who  use 
tobacco  in  this  form.  These  poisons  are  absorbed  in  small 
quantities  by  the  mucous  membrane  which  lines  the  nasal 
passages  and  in  larger  quantities  when  the  smoke  is  in- 
haled in  the  lungs. 

A  simple  way  to  prove  that  cigarette  smoke  contains  a 
poison  is  by  blowing  the  smoke  through  a  glass  tube  into 
an  aquarium  containing  goldfish.  Only  a  small  amount 
of  smoke  wrill  kill  the  fish. 

While  we  can  all  gradually  adapt  ourselves  to  small 
amounts  of  poison,  poisons  are  never  beneficial  unless  pre- 
scribed by  a  physician  to  try  to  remedy  some  bodily  defect. 
The  poisons  which  arise  from  the  burning  of  a  cigarette 
are  never  prescribed  even  as  medicines,  and  have  never 
been  found  in  any  way  beneficial  to  the  human  body. 

SUMMARY 

The  nervous  system  of  all  vertebrates  consists  of  a  brain 
and  spinal  cord  with  nerves  passing  to  all  organs  of  the 
body.     The  brain  of  man  is  the  most  highly  developed. 

All  our  movements  are  controlled  by  means  of  the  nerv- 
ous system.  Through  our  sense  organs  we  gain  our 
information  of  the  world. 

The  nervous  system  is  made  up  of  cells  which  are 
highly  specialized.  Their  main  work  is  to  transmit  and 
interpret  stimuli.  The  nerves  of  man  are  so  highly  spe- 
cialized that  all  stimuli  which  affect  the  eye  are  thought 
1  >  v  us  to  be  light  stimuli ;  or  all  stimuli  which  enter  in 
the  ear,  seem  to  be  sounds.  The  information  which  passes 
over  any  of  our  special  sense  organs  travels  over  several 


QUESTIONS  231 

different  nerve  cells  before  it  reaches  the  place  in  the 
brain  where  it  is  interpreted.  The  highly  specialized 
nervous  system  and  sense  organs  grow  and  arc  fed  just 
as  muscles  or  skin  grow  and  are  fed.  There  is  n<>  Bpecial 
food  which  we  can  eat  that  is  used  exclusively  by  the 
nervous  system. 

QUESTIONS 

What  is  the  nervous  system?  Of  what  parts  is  it  composed? 
What  animals  have  you  studied  that  have  a  nervous  system  ?  Which 
ones  lacked  a  special  nervous  system?  How  docs  the  nervous  system 
grow?  Describe  the  nerve  cell.  How  docs  it  differ  from  other  cells 
in  man?  What  are  special  senses  ?  What  kind  of  information  do  you 
receive  through  your  eyes?  What  kind  through  your  tars  ?  Which  d<> 
you  remember?  (The  well-trained  mind  remembers  equally  well  the 
information  that  comes  in  through  each  of  his  sense  organs. ) 

To  most  of  us  it  is  given  to  play  an  unimportant  n">l<' 
in  the  period  in  which  we  live.  Inheriting  from  our 
parents  healthy,  normal  bodies  we  can  at  least  pass  on 
this  priceless  heritage  to  our  children.  It  will  be  their 
chief  pride,  as  it  is  ours.  Life  is  not  easy,  and  we  need 
the  best  bodies,  the  best  nervous  systems,  ami  tin*  besl 
trained  minds  that  it  is  possible  for  us  to  have  in  order 
to  make  our  lives  count  for  the  most.  This  means  that 
it  is  the  duty  of  every  boy  and  girl  to  know  about  sani- 
tation, public  and  private  hygiene,  and  disease. 

REFERENCES 

Cutten,  The  Psychology  of  Alcoholism. 

Davenport,  Heredity  in  Relation  to  Eugenics. 

Guyer,  Being  Well-born. 

Horsley  and  Sturge,  Alcoholism  and  the  Human  Body 


CHAPTER   XIX 

* 

THE  BIOLOGY  OP  DISEASE1 

STUDENT  KEPORT 

How  many  in  the  class  have  been  sick  during  the  past  year  ?  Of  how 
many  different  diseases  ?  What  was  done  to  aid  each  one  in  getting 
well  ?  What  was  done  to  prevent  others  from  taking  the  same  diseases  ? 
What  was  done  by  your  Board  of  Health  officer  ?  (Consult  the  reports 
of  the  State  Board  of  Health  and  of  the  local  health  official.) 

173.  Disease. — Usually  people  go  through  their  daily 
occupations  without  feeling  pain  or  bodily  discomfort. 
Such  a  condition  is  known  as  health.  Sometimes,  how- 
ever, they  go  about  their  usual  duties  when  they  do  not 
feel  well  and  the  indisposition  gradually  passes  away. 
But  in  other  cases  the  ill  feeling  becomes  severe,  the  usual 
activities  are  given  up,  and  we  say  that  they  are  sick. 
Sickness  may  last  for  only  a  short  time  or  for  many  years. 
The  usual  conditions  of  the  body  are  changed,  and  we  say 
that  the  body  is  diseased.  The  apple,  the  tree,  the  dog, 
the  horse,  each  has  its  own  diseases. 

174.  Cause  of  Disease.  —  While  there  are  many  causes  of 
disease,  all  of  them  may  be  grouped  under  four  headings: 
(1)  Inherited  diseases,  i.e.  those  transmitted  from  parent 
to  child,  as  certain  forms  of  insanity  and  imbecility  where 
the  exact  cause  is  not  known.  (2)  Diseases  caused 
by  such  poisons  as  lead,  arsenic,  mercury,  phosphorus, 
opium,  cocaine,  alcohol,  and  the  like.  The  disturbances 
which  these  chemical  agents  set  up  in  animal  tissues  are 

1  Chapter  XXII,  Bacteria,  may  be  read  in  connection  with  this  chapter. 

232 


COMMUNICABLE   DISEASES  233 

easily  recognized  by  a  good  physician.  (3  )  I  diseases  which 
cause  certain  tissues  to  take  on  an  abnormal  growth,  as  in 
tumors  and  cancers.  (4)  Diseases  caused  directly  or 
indirectly  by  some  definite  living  plant  or  animal.  Such 
diseases  are  called  "  biological  diseases,"  because  the  source 
or  cause  is  in  all  instances  some  definite  living  plant  or 
animal.  In  our  ordinary  daily  speech  we  often  speak  of 
such  ills  as  "  germ  "  diseases. 

175.  Biological  Diseases. — The  rattlesnake  secretes  a 
poison  which  is  forced  through  fangs  or  hollow  teeth  into 
the  blood  of  its  prey.  This  poison  affects  the  heart  and 
may  result  in  death.  One  of  the  common  and  beautiful 
mushrooms  produces  a  similar  poison  which  is  nut  de- 
stroyed by  cooking.  If  this  particular  mushroom  is  eaten, 
death  is  almost  certain  to  follow  in  from  twenty-four  to 
forty-eight  hours.  In  both  of  these  cases  the  animal  or 
plant  is  large  enough  to  be  seen  and  easily  recognized. 

But  there  are  a  considerable  number  of  microscopic 
plants  and  a  few  microscopic  animals  that  have  formed  the 
habit  of  living  for  at  least  a  part  of  their  life  in  other 
plants  and  animals.  During  this  time,  as  we  have  seen  in 
the  study  of  animal  parasites,  they  usually  secure  all,  or  the 
greater  part,  of  their  food  from  the  plant  or  animal  in 
which  they  are  living.  Two  general  causes  of  disease  re- 
sult from  this  parasitic  habit.  The  parasite  may  destroy 
certain  cells  of  the  body,  or  the  material  thrown  off  from 
the  body  of  the  parasite  may  act  as  a  specific  poison. 

176.  Communicable  Diseases.  —  The  term  communicable 
disease 1  is  used  in  this  book  to  mean  the  diseases  caused  by 


1  New  York  State  designates  t be  following  as  communicable  diseases: 
anthrax;  chickenpox;  cholera,  Asiatic:  diphtheria  (membranous  croup); 
dysentery,  amoebic  and  bacillary  ;  epidemic  cerebrospinal  meningitis;  epidemic 

or  streptococcus  (septic)  sore  throat:   German  measles:    glanders;   measles; 
mumps;  ophthalmia  neonatorum;  para-typhoid  lever:  plague;  poliomyelitis, 


234  THE  BIOLOGY  OF   DISEASE 

a  plant  or  animal  living  as  a  parasite  in  plants,  animals,  or 
man.  These  diseases  are  communicated  in  various  ways 
from  one  individual  to  another,  from  one  animal  to  an- 
other, or  from  one  plant  to  another. 

The  following  are  among  the  most  common  communi- 
cable diseases.  Diseases  caused  by  bacteria  (minute  plants) 
are  tuberculosis,  pneumonia,  diphtheria,  typhoid  fever, 
bubonic  plague,  and  whooping  cough.     Measles  and  scarlet 

fever  are  so  similar  to 

I  these    in    many    ways 

that  it  is  believed  that 
they    are    caused    by 
^_      ^^  bacteria,  although  the 

^_       ^^      definite  bacteria  which 
cause   them    have    not 
been  discovered.     Dis- 
eases caused  b}^  proto- 
■    ?  rp      -a    o  wi  zoa   (minute    animals) 

Diphtheria    Measles      Tvphoid      Scarlet     Whooping  ^  ' 

fever        cough      are      malaria,      yellow 
Figure  238.  —  Deaths  from  Communicable     fever       sleeoina"     sick- 
Diseases.  '  ,*      ° 

,    ,       ness,     possibly     small- 
This  is  for  the  year   1913  in  New  York  r  J 

State.  pox,    and    others    less 

well  known. 
The  biological  diseases  are  all  preventable,  especially 
the  communicable  diseases  which  result  from  the  parasitic 
habit  of  some  plant  or  animal.  In  order  to  prevent  these 
diseases,  it  is  necessary  to  know  how  the  different  plants 
and  animals  gain  access  to  the  human  body  and  proceed 
to  live  there.  This  can  be  illustrated  by  describing  pul- 
monary tuberculosis,  a  plant  or  bacterial  disease ;  and 
malaria,  an  animal  or  protozoan  disease. 


acute  anterior  (infantile  paralysis);  puerperal  septicaemia;  rabies;  scarlet 
fever ;  smallpox ;  trachoma ;  tuberculosis ;  typhoid  fever ;  typhus  fever ; 
whooping  cough. 


Robert  Koch  (1843-1910)  was  a  celebrated  German  physician, 
noted  as  the  discoverer  of  the  bacilli  of  tuberculosis  and  of  cholera. 

In  1882  he  announced  in  Berlin  the  discovery  of  the  tubercle 
bacillus,  and  the  same  year  he  published  a  method  of  preventive 
inoculation  against  anthrax.  Later  he  discovered  tuberculin,  a 
substance  intended  to  check  the  growth  of  the  tubercle  bacillus. 

In  1883,  Koch  led  the  German  expedition  to  India  to  investi- 
gate cholera,  and  discovered  the  cholera  germ.  In  1885  he  be- 
came Professor  of  Medicine  at  Berlin  and  in  1891  Director  of  the 
new  Institute  for  Infectious  Diseases. 


PULMONARY    TUBERCULOSIS  235 

177.    Pulmonary  Tuberculosis.  —  Pulmonary    tuberculosis 

is  a  disease  located  in  the  lungs.  The  cause  is  ;i  definite 
plant  with  parts  and  habits  which  are  easily  recognized  by 
bacteriologists  (students  of  bacteria).  This  plant  is  called 
Bacillus  tuberculosis,  and  was  proved  to  be  the  cause  of 
consumption,  or  tuberculosis,  by  Robert  Kocli,  a  German 
scientist,  in  1882.  These  tuberculosis  bacteria,  or  germs, 
in  countless  numbers  are  found  leading  a  parasitic  life  in 
the  lungs  of  a  tubercular  patient.  The  bacteria  are  ex- 
tremely minute,  and  can  be  seen  only  by  the  use  of  a 
microscope  of  high  power. 

The  large  number  of  germs  in  the  lungs  grow  rapidly 
and  they  are  set  free  in  the  air  by  coughing.  One  tuber- 
culosis patient  may  give  off  millions  of  these  germs  in  a 
day.  For  this  reason  great  care  should  be  taken  in  destroy- 
ing the  sputum  of  patients,  for  if  the  germs  become  dry. 
they  are  carried  about  as  dust  particles. 

Tuberculosis  and  other  disease  germs  are  so  numerous 
that  it  is  impossible  to  escape  taking  some  of  them  into  our 
bodies,  but  they  usually  do  us  no  harm  unless  we  are  in  a 
weakened  condition. 

Modern  methods  of  cleaning  the  streets  by  flushing  witli 
water,  keeping  garbage  covered,  and  wiping  up  tin-  dust 
in  our  homes  instead  of  using  the  old-fashioned  feather 
duster  are  doing  much  to  keep  down  the  number  of  germs 
in  the  air  which  we  breathe. 

The  bacteria  that  are  breathed  in  from  the  air  may  find 
some  weak  place  in  the  lungs  in  which  to  take  up  their 
parasitic  lives.  Those  which  enter  on  the  food  pass  from 
the  digestive  tract  into  the  blood  and  are  eventually  carried 
to  the  lungs.  The  introduction  of  tuberculosis  germs  in 
this  way  is  especially  frequent  in  children.  In  many 
cases  milk  from  tuberculous  cows  is  the  source  of  the 
disease  germs.     See  §  248,  page  34(.*. 


236 


THE   BIOLOGY  OF   DISEASE 


The  cause  of  pulmonary  tuberculosis  is,  then,  the  tuber- 
cle bacillus,  which  is  taken  into  the  lungs  in  the  air  we 
breathe,  or  through  the  food  eaten,  or  by  personal  contact 
with  a  consumptive  patient.  These  germs  cause  certain 
parts  of  the  lungs  to  become  diseased. 

178.  Getting  Well.  —  Consumption  is  not  necessarily 
fatal,  especially  if  treated  in  its  earliest  stages.     But  many 


Figure  239. —Tuberculosis  Cure,  Summer. 


people  who  have  the  disease  do  not  consult  a  regular 
physician  until  it  has  made  considerable  progress,  and 
then  it  is  too  late  to  bring  about  a  cure. 

Figures  239  and  240  show  the  present  method  used  in 
treating  tuberculosis.  The  patients  are  given  tissue-build- 
ing food  (protein)  and  are  required  to  sit  and  sleep  out- 
of-doors  as  much  as  possible.  Rest,  good  food,  and  fresh 
air  work  wonders  in  arresting  the  progress  of  this  disease. 

When  the  body  gains  the  requisite  amount  of  strength 


MALARIA.      A    PROTOZOA X    DISEASE 


'IM 


the  disease  and  its  germs  are  usually  thrown  off.  Patent 
medicines  and  alcohol  should  be  avoided,  as  they  reduce 
the  power  of  the  body  to  resist  disease  and  give  no  aid 
in  building  up  the  diseased  tissues.      In  addition,  alcohol 

causes  serious  disturbances  in  the  general  circulation. 


Figure  240.  —  Tuberculosis  Cure,  Winter. 


In  addition  to  pulmonary  tuberculosis  physicians  recog- 
nize tuberculosis  of  the  throat,  intestines,  kidneys,  brain, 
and  joints. 

179.  Malaria.  A  Protozoan  Disease. — Malaria  is  a  disease 
caused  by  a  protozoan  or  minute  animal  which  is  dis- 
tributed over  the  greater  part  of  the  world.  The  malaria 
protozoan  is  a  minute  simple  cell  of  living  matter.  It 
resembles  the  amreba  in  its  form  and  ability  to  chancre. 
This  parasite  penetrates  into  the  red  blood  corpuscles  and 
remains  in  them  for  twenty-four  or  forty-eight  hours,  or 
until   the  substance  of  the   corpuscle   is  nearly   used    up. 


238 


THE   BIOLOGY  OF   DISEASE 


Then  the  parasite  escapes  into  the  plasma  of  the  blood  and 
later  enters  a  fresh  corpuscle. 

180.  Source  of  the  Malarial  Parasite.  —  The  word  malaria 
means  bad  air,  for  it  was  formerly  believed  that  foul  air 
caused  the  disease.  When  it  was  learned  that  a  definite 
animal  was  the  cause  both  in  man  and  in  other  animals, 
the  problem  was  to  find  how  the  parasite  entered  the  bod}^ 


Figure  241. —  Malarial  Swamp. 
An  ideal  place  for  mosquitoes  to  breed.  ] 

It  has  been  proved  to  the  satisfaction  of  scientists  that  the 
malarial  protozoan  is  injected  into  the  blood  by  a  particular 
kind  of  mosquito  (Anopheles)  which  carries  malaria  germs 
in  its  body. 

The  mosquito  sucks  the  blood  from  a  man  or  an  animal 
suffering  from  malaria.  This  blood  contains  some  of  the 
malarial  parasites,  which  pass  into  the  stomach  of  the  mos- 
quito. They  then  migrate  into  the  salivary  glands  of  the 
mosquito,  so  that  as  soon  as  the  mosquito  bites  another 
man  or  animal,  it  pours  out  some  saliva  which  intro- 
duces the  parasites  into  the  victim's  blood.     While  in  the 


PREVENTION  OF   COMMUNICABLE   DISEASES      239 

body  of  the  mosquito,  these  parasites  pass  through  definite 
stages  in  their  life  history;  and  when  they  reach  tin- 
blood  of  man,  the  remaining  stages  are  completed.  Thus 
a  man,  or  an  animal,  and  a  particular  mosquito  are  neces- 
sary for  the  complete  life  history  of  the  malarial  parasite. 
This  means  in  addition  that  for  the  prevention  of 
malaria  all  that  is  necessary  is  to  destroy  the  Anopheles 
mosquito,  or  in  case  this  cannot  be  done,  to  screen  ade- 
quately the  houses,  tents,  and  bedrooms  in  the  regions 
where  the  mosquitoes  live.  It  is  interesting  to  note  that 
this  discovery  of  the  cause  of  malaria  and  the  methods  for 
its  prevention  was  more  than  anything  else  responsible  for 
the  successful  completion  of  the  Panama  Canal.  The  con- 
struction of  this  important  work  was  more  a  health  than 
an  engineering  problem. 

181.  Other  Protozoan  Diseases. —  Other  protozoan  dis- 
eases are  produced  in  the  same  manner  as  malaria.  The 
carrier  may  be  different,  but  the  principle  of  spreading 
the  diseases  is  the  same.  Yellow  fever,  for  instance,  is 
spread  by  another  kind  of  mosquito,  and  sleeping  sickness 
by  the  tsetse  fly. 

182.  Hookworm  Disease.  —  This  disease  is  caused  by  a 
parasite  which  is  classified  as  one  of  the  worms.  Hook- 
worm disease  belts  the  earth  in  a  zone  which  extends  thirty - 
three  degrees  each  side  of  the  equator.  Great  progress 
is  being  made  in  the  United  States  in  curing  those  su lin- 
ing from  this  disease.  The  wearing  of  shoes  and  the  use 
of  a  sanitary  closet  are  usually  sufficient  preventives  bo 
protect  the  people  who  live  in  a  hookworm  district. 

183.  Prevention  of  Communicable  Diseases. — The  pre- 
vention of  these  diseases  depends  upon  an  understanding 
of  the  causes  which  produce  them,  close  adherence  to  the 
laws  of  hygiene,  and  especially  the  exercising  of  proper 
care  in  the  production  and  cooking  of  our  food.     Germ 


240  THE  BIOLOGY  OF   DISEASE 

diseases  are  unnecessary,  and  it  should  be  considered  a 
disgrace  to  a  community  if  some  of  them  appear.  Proper 
hygienic  measures  will  do  much  towards  eliminating 
most  of  the  communicable  diseases,  but  until  the  intelli- 
gence of  communities  can  be  aroused  enough  so  that  such 
measures  shall  be  insisted  upon,  we  must  depend  upon 
proper  food,  rest,  fresh  air,  and  exercise  to  keep  ourselves 
fit,  and  thus  avoid  the  conditions  which  help  disease  to 


■     TLa  ■  .hu'.ihlT^*j< 

_^0 

*  -  ___           — 

■  ■  .      ■ 

K      ^H 

'■   1 

Figure  242.  —  A  Model  Reservoir. 

gain  a  foothold.  Tuberculosis,  for  example,  is  more  likely 
to  occur  in  persons  who  are  underfed  and  overworked, 
and  a  cold  often  follows  an  attack  of  indigestion. 

Care  of  Food.  —  The  care  of  food  is  extremely  neces- 
sary in  preserving  our  bodily  well-being,  for  the  same 
germs  live  and  grow  in  food  which  cause  disease  when 
taken  into  our  bodies.  One  method  of  keeping  the  bac- 
teria on  food  from  growing  is  by  proper  refrigeration. 
The  temperature  of  a  well-cooled  refrigerator  does  not 
destroy  the  germs,  but  makes  them  incapable  of  growth 
until  heat  is  supplied  them.  So  if  food  is  taken  from  the 
refrigerator  and  allowed  to  stand  for  a  time,  the  bacteria 
will  at  once  begin  to  grow  and  cause  the  food  to  spoil. 


PREVENTION  OF   COMMUNICABLE   DISEASES     241 

If  such  food  is   eaten,   an  intestinal  disturbance  usually 
results. 

In  the  attempts  to  prevent  disease,  more  study  has  been 
given  to  milk  and  water  than  to  other  foods.  For  discus- 
sion of  milk,  see  pages  347-350. 

While  milk  is  used  as  a  food  by  all  mankind,  water  is 
even  more  important,   for  it  is  absolutely  necessary  if  we 


Figure  243. — A  Poor  Reservoir. 

Note  the  open  stream  that  empties  into  the  main   body  of  water. 
The  impure  water  of  the  Erie  Canal  drains  into  this  open  stream. 

are  to  continue  to  live.  In  this  respect  man  is  like  all 
plants  and  all  other  animals,  water  being  necessary  for 
the  preservation  of  all  life. 

Two  conditions  must  be  met  before  a  water  supply  can  be 
deemed  satisfactory.  There  must  be  an  abundant  supply; 
but  more  important  still,  the  water  must  be  pure,  that  is, 
free  from  disease-producing  germs.  Farmers  and  residents 
of  small  towns  ma}r  without  great  trouble  secure  sufficient 
pure  water,  but  the  large  cities  have  to  spend  millions  of 
dollars  in  providing  an  adequate  water  supply. 


242 


THE  BIOLOGY  OF  DISEASE 


Sanitary  measures  are  adopted  to  keep  the  sources  of 
the  water  from  becoming  impure,  as  well  as  to  keep  clean 
the  reservoir  where  it  is  stored.  Certain  harmless  plants 
and  animals  living  in  reservoirs  may  give  an  unpleasant 
taste  or  odor  to  the  water.  Harmful  disease  germs  live 
in  water  for  months.  Such  germs  may  be  frozen  in  ice, 
stored  in  ice  houses,  and  when  later  put  with  the  ice  into 
drinking  water,  may  cause  typhoid  fever.     It  is,  therefore, 

important  that  we  have 
plenty  of  pure  water,  and 
we  should  do  all  we  can 
to  help  in  giving  the 
town  or  city  in  which  we 
live  a  pure  water  supply. 


Introduction  of 
Antitoxin  Treatment 


STUDENT   REPORT 

Prepare  a  report  on  the  water 
supply  in  your  locality  and  find 
where  it  comes  from.  What 
measures  are  taken  to  keep  the 
sources  and  reservoir  clean  ? 

184.  Keeping  Well.  — 
Our  best  doctors  are 
spending  much  effort  in 
showing  how  to  avoid 
disease,  for  no  one  is 
benefited  by  illness.  The 
old  notion  that  children  should  be  exposed  to  measles, 
scarlet  fever,  and  whooping  cough  is  wrong,  for  none  of 
these  childhood  diseases  is  necessary.  The  time  will  come 
when  our  homes  and  surroundings  will  be  so  sanitary 
that  the  common  diseases  caused  by  germs  will  be  elimi- 
nated, or  at  least  decreased  in  number. 

Government  inspection  of  meats  is  lessening  the  amount 


1881  87    89    91    93   '95  '97       1900  02   04   06   08    10     12     14 

Figure  244.  —  Diagram. 

Thirty  years  of  diphtheria  in  New 
York  State. 


KEEPING   WELL  243 

of  disease  contracted  from  eating  diseased  pork,  incut,  and 
fish.  The  United  States  Department  of  Agriculture  is 
making  every  effort  to  inspect  such  products,  and  tin- 
department  is  fairly  successful  in  inspecting  the  larger 
establishments.  However,  many  cattle  and  hogs  are  killed 
and  sold  locally  and  they  escape  inspection,  so  that  buyers 

IF 
THESE  CASES  THESE  CASES 

HAD  BEEN  REPORTED  WOULD  r^VER  MAVE  OCCURRED 


JO 


25 


3l5 


S 

Ct 

|:0 


*■ 


On  Fabm  On  Faom 

J I 1J 

M      17      21  30  I  2   4     6    6    10   12  14  16   «  20 

Mm  S     7    9    II    13  15  17  19 

June 


21  .     ,       27  9    II  M      17      21  30  I  2   4     6    6    10   12  14  16   «  20  23  JO 

Afri  Mm  5    7   9    ll   13  15  17  19  T 


The  Story  of  the  Epidemic  op  Septic  Soke  Throat  at  Rockvoxe  Centre.  L.  I. 

Figure  245. 

of  this  meat  have  no  protection  against  a  general  condition 
of  disease. 

Another  danger  to  health  is  from  the  people  known  as 
"carriers"  of  disease,  as  such  people  give  no  evidences  of 
illness.  Typhoid  and  diphtheria  are  the  two  diseases 
most  likely  to  be  carried  in  this  way.  Many  of  these 
carriers  serve  as  cooks,  and  as  they  give  no  evidence  of 
being  in  other  than  perfect  health,  they  often  spread  the 
germs  through  the  food  they  prepare.  If  habits  of  abso- 
lute cleanliness  are  insisted  upon,  much  of  the  danger  of 
the  dissemination  of  srerms  in  this  way  will  be  removed. 


244  THE  BIOLOGY   OF   DISEASE 

Many  hotels,  public  institutions,  and  well-run  house- 
holds insist  that  a  prospective  servant  shall  be  examined 
by  a  competent  physician  before  being  engaged  for  work. 
In  this  way  carriers  may  be  detected,  and  persons  with 
germ  diseases,  like  tuberculosis,  for  instance,  are  pre- 
vented from  spreading  disease  either  in  the  food  or  in 
the  air. 

(  hildren  in  the  schools  frequently  have  diphtheria  germs 
living  in  their  nasal  passages  or  throats,  but  are  not  ill. 
After  a  time  a  number  of  children  come  down  with  the  dis- 
ease. A  doctor  then  takes  a  sample  of  the  contents  of  the 
throat  and  nose  of  each  child.  The  bacteria  in  the  mucus 
from  the  nasal  passages  is  allowed  to  grow  for  twenty-four 
hours  in  a  special  preparation  called  a  culture  (page  346). 
At  the  end  of  that  period  the  cultures  are  stained  and  ex- 
amined with  a  high  power  of  the  microscope,  and  if  diph- 
theria germs  are  present,  they  are  easily  seen.  If  one  of 
the  well  children  has  these  germs,  he  is  treated  until  they 
disappear. 

185.  Quacks  and  Patent  Medicines.  —  The  term  quack  is 
applied  to  a  person  who  advertises  that  he  can  cure  vari- 
ous diseases  by  some  new  invention  or  newly  discovered 
remedy.  A  patent  medicine  is  one  which  has  been  regis- 
tered at  the  patent  office,  and  this  registration  gives  the 
patentee  exclusive  right  to  the  use  and  name  of  the  so- 
called  remedy.  Many  millions  of  dollars  are  spent  an- 
nually in  advertising  special  "  cures  "  and  new  mechanical 
contrivances  guaranteed  to  cure  diseases  for  which  they 
can  do  nothing,  or  even  to  cure  such  diseases  as  cancer, 
for  which  there  is  no  known  remedy. 

Many  people  who  do  not  understand  the  causes  of  dis- 
ease are  reluctant  to  consult  a  well-trained  physician,  but 
read  and  believe  the  carefully  worded  advertisement  of 
some    quack  doctor    or  of   some    patent   medicine.     The 


ALCOHOL  AND   DISEASE  245 

untrained  sufferer  cannot  interpret  the  meaning  of  his 
distress  and  is  incompetent  to  select  the  proper  medicine. 
As  real  medicine  is  given  for  specific  symptom-  associated 
with  a  specific  disease,  it  is  apparent  that  ;i  patent  medi- 
cine advertised  to  cure  from  six  to  forty  diseases  is  worth- 
less. Furthermore,  real  medicine  is  given  to  relieve  a 
certain  set  of  symptoms  at  a  given  stage  of  the  disea 
and  is  frequently  changed.  This  is,  of  course,  impossible 
when  using  a  patent  medicine.  If  every  one  would  eon- 
suit  regular  physicians,  and  cease  patronizing  the  quacks 
and  patent  medicines,  one  of  the  sources  of  much  sickness 
and  suffering  would  be  destroyed. 

186.  Alcohol  and  Patent  Medicine.  —  Repeated  chemical 
analysis  of  many  of  the  patent  medicines  shows  that  they 
contain  a  considerable  amount  of  alcohol.  There  are  over 
120  patent  medicines  which  the  United  States  Government 
will  not  permit  to  be  sold  except  by  the  possessor  of  a 
liquor  license.  This  fact  alone  shows  the  harmful  nature 
of  patent  medicine. 

187.  Alcohol  and  Disease.  —  It  is  unnecessary  to  make  an 
elaborate  series  of  quotations  from  eminent  men  to  prove 
that  alcohol  is  not  useful  and  necessary  as  a  medicine  in 
the  cure  of  disease.  One  of  the  chief  reasons  has  already 
been  given  in  connection  with  the  discussion  of  tubercu- 
losis. There  is  no  evidence  that  alcohol  has  any  effect  "ii 
the  destructive  course  of  a  disease,  or  any  beneficial 
effect  upon  the  person  suffering  from  disease.  This  last 
phase  of  the  problem  has  been  under  critical  study  Long 
enough  to  show  that  the  earlier  claims  of  the  helpful- 
ness of  alcohol  in  disease  are  not  supported  by  the  facts. 
The  reverse  is  true.  Alcohol  is  known  t«>  decrease  the 
power  of  the  body  to  withstand  disease  and  dm>s  not 
assist  in  destroying  the  poisons  which  arise  in  the 
case    of    bacterial    diseases.       At    present     there     is     no 


246  THE   BIOLOGY   OF   DISEASE 

scientific  evidence  which  justifies  the  use  of  patent 
medicines,  or  of  alcohol  unless  definitely  prescribed  by  a 
physician. 

188.  Headache  and  Anti-pain  Patent  Medicines.  —  Many 
preparations  advertised  under  these  general  names  are 
taken  by  persons  ignorant  of  the  fact  that  these  medicines 
generally  contain  harmful  drugs.  It  should  be  sufficient 
to  know  that  no  reputable  doctor  will  ever  give  any  of 
these  preparations  except  in  a  mild  form,  and  in  case  of 
extreme  pain.  No  person  except  a  trained  physician  has 
a  right  to  prescribe  drugs  ;  and  he  only  after  a  knowledge 
of  the  patient's  symptoms.  Many  of  these  preparations 
affect  the  heart  and  blood,  and  none  of  them  has  any 
beneficial  effect  on  the  real  cause  of  the  pain. 

189.  Boards  of  Health.  —  Communities  and  physicians 
have  endeavored  to  prevent  the  spread  of  communicable 
diseases  by  the  formation  of  boards  of  health,  by  quaran- 
tine, vaccination  against  smallpox,  immunization  against 
typhoid  fever,  the  use  of  antitoxin  in  diphtheria,  disin- 
fectants and  fumigants. 

The  term  Board  of  Health  is  applied  to  a  number  of 
individuals,  appointed  or  elected  by  a  nation,  b}^  a  state,  or 
by  a  community,  to  enforce  the  national,  state,  city,  or  town 
health  laws  and  regulations.  The  local  officer  of  this  board 
is  a  physician,  and  in  some  states,  New  York  for  example, 
is  appointed  according  to  the  regulations  governing  the 
city  or  town  in  which  he  is  to  serve.  The  New  York  state 
law  defines  his  work  as  follows  : 

"  Every  such  local  officer  should  guard  against  the  intro- 
duction of  such  communicable  diseases  as  are  designated 
by  the  State  Department  of  Health  by  the  exercise  of 
proper  and  vigilant  medical  inspection  and  control  of  all 
persons  and  things  infected  with  or  exposed  to  such 
diseases,  and  provide  suitable  places  for  the  treatment  and 


QUARANTINE 


247 


care  of  sick  persons  who  cannot  otherwise  be  provided 
for."1. 

Violation  of  quarantine  and  of  the  various  health  regu- 
lations, such  as  the  pollution  of  water  and  improper  care 

of  refuse  and  sewage,  should  be  reported  to  the  local  health 
officer.  In  case  no  satisfactory  results  are  obtained  from 
the  local  health  officer,  the  question  may  be  referred  to  the 


Figure  246.  —  Model  Dairy  Cow. 


State  Board  of  Health,  which  gives  prompt  and  efficient 
attention  to  all  questions  concerning  the  health  of  the 
people  of  the  state. 

190.  Quarantine.  —  When  a  person  or  a  group  of  persons 
is  suffering  from  a  communicable  disease,  or  when  anyone 
has  been  exposed  to  the  germs  of  the  infection  of  any 
such  disease,  the  Board  of  Health  may  place  him  under 
quarantine.     The  nature  of  the  quarantine  depends  OD  the 


JThe  Sanitary  Code  of  the  Public  Health  Council  of  the  State  of  NYw 
York  defines  the  health  officer's  duties  in  detail  and  may  be  had  by 
writing  to  the  State  Department  of  Health  at  Albauy.  Selections  from 
the  Sanitary  Code  will  be  found  in  Appendix  B. 


248 


THE  BIOLOGY  OF   DISEASE 


specific  disease  and  the  laws  of  the  town  or  state  in  which 
the  persons  reside. 

The  New  York  law  on  this  subject  is  typical  of  the  best 
state  laws  on  quarantine.     It  says  : 

"The  Board  of  Health  shall  prohibit  and  prevent  all 
intercourse  and  communication  with  or  use  of  infected 
premises,  places,  and  things  ;  and  require  and  if  necessary 


Figure  247.  —  Model  Dairy  Stable. 

provide  the  means  for  the  thorough  purification  and  chang- 
ing of  the  same  before  general  intercourse  with  the  same 
or  use  thereof  shall  be  allowed."     See  Appendix  B. 

This  means  if  an  individual  is  suffering  from  scarlet 
fever  or  diphtheria,  or  some  other  communicable  disease, 
he  shall  not  associate  with  the  general  public  until  he  has 
ceased  to  be  a  source  of  infection.  His  liberty  is  tempo- 
rarily restricted  by  quarantine  because  he  may  be  the 
cause  of  sickness  and  even  death  to  others  by  spreading 
the  germs  of  communicable  disease. 

It  is  interesting  to  know  that  the  more  highly  civilized 


QUARANTINE 


249 


00 

D 
O 


a; 


SZ 


JZ 

o 


n- 

4) 

<u 

jz 
o 

c 


o 


sz 

JZ 
tn 

c 

4> 

To 

,c 
o 


a  nation,  state,  or  city  becomes,  the  more  specific  and 
exacting  are  the  quarantine  regulations.  There  is  every 
reason  to  believe  that  in  the  near  future  the  present  laws 


250 


THE  BIOLOGY  OF   DISEASE 


of  quarantine  will  be  extended.  In  addition  to  individuals 
being  quarantined  in  a  dwelling,  all  the  inhabitants  of  a 
city  or  state  may  be  quarantined  in  case  of  severe  epi- 
demics ;  or  the  transportation  of  stock  from  one  state  to 
another  may  be  prohibited  in  the  case  of  a  serious  com- 
municable disease  existing  in  cattle  or  sheep.  The  quar- 
antine laws,  for  example,  order  from  time  to  time  that  all 

dogs  in  the  town  or 
county  shall  be  muzzled 
as  a  protective  measure 
against  rabies. 

Immigrants  suffering 
from  certain  diseases  are 
prohibited  from  landing 
in  the  United  States. 
This  means  that  there 
are  national  as  well  as 
state  and  city  quaran- 
tine laws.  The  present  quarantine  laws  are  the  most 
effective  protective  measures  against  the  spread  of  disease 
known  to  man  and  are  the  product  of  a  high  degree  of 
civilization. 

191.  Vaccination.  —  The  success  which  has  attended  the 
efforts  of  man  to  overcome  disease  is  well  illustrated  hy 
smallpox.  For  centuries  this  disease  was  responsible  for 
many  deaths  throughout  the  world.  It  is  said  to  have 
existed  in  China  centuries  before  Christ.  Later  it  swept 
over  Europe  again  and  again.  King  Frederick  William 
III  of  Prussia  stated,  in  1803,  that  40,000  people  suc- 
cumbed annually  in  his  kingdom.  A  famous  French 
physician  wrote  in  1754  that  every  tenth  death  was  due 
to  smallpox,  and  that  one  fourth  of  mankind  was  either 
killed  by  it  or  disfigured  for  life.  Smallpox  was  brought 
into  the  Western    Hemisphere   soon  after   the  discovery 


Figure  249.  —  Agar  Plates. 

Where  a  house  fly  was  allowed  to  walk 
White  patches  are  bacterial  growths. 


VACCINATION 


2.->l 


of  America  and  killed  thousands  of  the  Indians.  It  also 
visited  the  colonies.  In  1721,  Boston  was  ravaged  foi 
the  sixth  time  by  this  disease.  Out  of  the  10,567  Inhabit- 
ants, 5989  had  the  disease  and  894  died. 

In  179G,  Jenner,  an  Englishman,  demonstrated  the  fact 
that  by  inoculation  of  a  person  with  cowpox,  a  disease 
peculiar  to  cows  and  in  some  way  allied  to  smallpox,  the 
patient  would  become  immune  to  the  dreaded  disease. 
This  was  one  of  the  greatest  and 
most  beneficial  discoveries  of  medi- 
cine which  has  ever  been  made. 

By  the  result  of  vaccination  small- 
pox has  become  a  rare  disease  in  the 
civilized  nations  of  the  world,  and  is 
least  prevalent  where  the  vaccination 
laws  are  the  most  stringent. 

Vaccination  for  smallpox  consists 
in  the  inoculation  of  the  human 
patient  with  vaccine,  a  substance 
secured  from  a   cow  sufferings   from 

O 

cowpox.       This     usually     causes     a 

slight  illness,  but  during  the  illness  the  patient  acquires 
a  power  which  enables  him  to  resist  the  germs  of  small- 
pox. This  acquired  power  of  resistance  is  called  im- 
munity. 

Many  people  do  not  understand  the  theory  of  vaccina- 
tion and  its  advantages,  and  have  opposed  its  use  through 
fear  of  acquiring  lockjaw  from  the  vaccine.  It  has  been 
established  that  proper  vaccine  matter  never  contains 
the  germs  of  lockjaw,  and  if  this  disease  occurs,  ii  is 
due  to  failure  in  keeping  the  arm  clean  during  the  period 
when  the  vaccination  scar  is  forming. 

Immunity  to  disease  is  now  being  produced  through 
inoculation.      The  patient  is  inoculated,  that   is,   there  is 


Figure  250.  —  Bacteria 
and  Mold. 

One  tenth  of  the  num- 
ber carried  by  one  house 
fly. 


252 


THE   BIOLOGY   OF   DISEASE 


introduced  into  his  circulatory  system  a  virus,  or  serum. 
Each  disease  has  its  own  virus,  as  the  vaccine  in  small- 
pox, and  this  virus  produces  a  mild  form  of  the  disease. 
This  causes  the  cells  to  become  resistant  to  the  germs  or 
microbes  of  the  specific  disease.  Inoculation  is  being 
widely  used  for  the  prevention  of  typhoid  fever.  All 
soldiers  are  required  to  take  this  treatment.  It  would 
be  desirable  for  all  people  to  become  immunized  against 

this  disease,  but  those 
who  travel  extensively 
and  thus  have  to  drink 
all  kinds  of  water  and 
milk  should  certainly 
undergo  this  treatment. 
Vaccination  and  im- 
munization reduce  the 
liability  of  death  in  case 
the  disease  is  acquired, 
but  they  do  not  ab- 
solutely prevent  the  disease.  If  a  vaccinated  or  immu- 
nized person  gets  an  overwhelming  number  of  germs,  he 
may  have  an  infection  of  a  slight  kind.  But  the  liability 
of  contagion  is  reduced  to  a  minimum. 

192.  Antitoxin.  — We  cannot  say  definitely  why  vaccina- 
tion and  immunization  act  as  they  do.  It  is  known  that 
if  a  poison  (toxin)  produced  during  a  case  of  diphtheria 
is  gradually  introduced  into  the  blood  of  a  horse,  a  sub- 
stance is  produced  which  destroys  the  injurious  effects  of 
the  diphtheria  poison.  The  serum  from  the  blood  of  the 
horse  is  called  antitoxin,  and  may  be  preserved  for  use  at 
any  time  to  destroy  the  influence  of  the  diphtheria  poi- 
son. A  given  amount  of  this  antitoxin  is  introduced  into 
the  blood  of  the  patient  suffering  from  diphtheria,  and 
this  usually  counteracts  the  disease.     This  treatment  has 


Figure  251.  —  Milk  Diluted  to  j-^- 

Left-hand   culture   from   clean   milk ; 
right-hand  culture  from  dirty  milk. 


DISINFECTION  AND   DISINFECTANTS  253 

saved  countless  lives.  It  is  estimated  that  in  the  ten 
years  after  the  discovery  of  the  diphtheria  antitoxin  the 

lives  of  a  million  children  were  saved  in  Franc-  alone. 
State  boards  of  health  usually  furnish  antitoxin  for  diph- 
theria and  lockjaw. 

LABORATORY    STUDY 

It  takes  five  pounds  of  sulphur  to  disinfect  a  room  which  contains 
1000  cubic  feet  of  air.  Three  ounces  of  forty  per  cent  formalin,  u>  which 
is  added  two  and  one  tenth  ounces  of  potassium  permanganate  will  also 
disinfect  the  same  sized  room.  Compare  the  cost  and  ease  with  which 
each  is  used. 

193.  Disinfection  and  Disinfectants. — The  time  when  dis- 
infectants shall  be  used  and  the  manner  of  disinfection 
have  been  considered  important  factors  in  preventing  the 
spread  of  communicable  diseases.  The  purpose  of  <1  ^in- 
fection is  to.  destroy  the  germs  lodging  on  clothes,  floors, 
carpets,  and  curtains.  People  who  care  for  the  sick 
should  know  where  the  germs  are  likely  to  be  and  how 
to  disinfect  places  where  they  have  found  lodgment. 
The  term  disinfectants  is  sometimes  incorrectly  applied 
to  deodorizers,  substances  which  are  used  to  destroy 
odors,  but  the  word  should  be  applied  only  to  substances 
which  destroy  germs  or  bacteria. 

Disinfectants  are  not  expensive,  and  few  of  the  patented 
preparations  are  as  satisfactory  as  the  common  ones  used 
by  boards  of  health.  Weak  solutions  of  carbolic  acid  and 
bichloride  of  mercury  are  chiefly  used  for  killing  the 
germs  on  the  hands  and  clothing,  or  f»»r  cleaning  tin- 
woodwork  in  the  sick  room.  Chloride  of  lime  is  used  to 
kill  the  germs  in  the  discharges  of  the  body,  and  Bulphur 
dioxide  and  formaldehyde  gas  for  the  final  killing  of  the 
germs  in  the  room  or  the  whole  hoitse  before  it  is  occupied 
again. 


254 


THE   BIOLOGY   OF   DISEASE 


Never  use  any  methods  of  disinfection  unless  they  have 
been  personally  recommended  to  you  by  a  physician  or  an 
expert  in  the  details  of  room  disinfection.  Do  not  rely 
upon  patented  solutions  and  methods.  The  latter  are  ex- 
pensive and  often  practically  worthless.1 

194.  Results  of  Disease.  —  In  New  York  State  for  the  year 
1909  there  were  reported  to  the  State  Board  of  Health 
138,315  cases  of  communicable  diseases.  There  were 
many. cases  that  were  not  reported,  so  that  this  is  not  to 
be  taken  as  the  highest  estimate  of  the  number  of  people 
who  were  sick  with  preventable  diseases.  During  the 
years  1913,  1914,  1915  in  the  same  state  the  following 
number  of  people  died  from  these  communicable  diseases. 

NUMBER    OF   DEATHS 

1913-1915 


1913 
1914 
1915 


Diphtheria 


1853 
2015 
1754 


Scarlet  Fever 


837 
687 
409 


Whooping  Cough 


818 
730 
749 


Measles 


1071 
839 
834 


Typhoid  Fever 


1018 
878 
750 


It  is  difficult  properly  to  measure  the  value  of  health  to 
the  community.  When  the  wage  earner  is  sick  and  is 
placed  in  quarantine,  the  loss  of  money  is  the  amount  he 
might  have  earned.  In  the  case  of  a  typhoid  fever  epi- 
demic the  total  loss  is  many  thousands  of  dollars.  Further, 
there  is  no  adequate  measure  of  the  sufferings  of  those 
who  die,  and  the  heartaches  of  those  who  survive.  But 
both  the  suffering  and  the  financial  loss  can  be  greatly 
lessened  by  improving  our  sanitary  laws  and  aiming  at  a 
better  state  of  health  for  all  the  people.     An  increase  in 

1  When  practicable,  it  is  well  to  have  the  local  health  officer  discuss 
such  subjects  as  disinfection  and  quarantine. 


IMMUNITY  2f)5 

taxes  to  provide  cleaner  streets,  public  playgrounds,  proper 

sewage  disposal,  and  adequate  inspection  of  milk,  meat, 
and  water,  is  really  an  economy.  For  although  such 
improvements  cost  money,  they  are  not  so  expensive  as 
epidemics  of  disease  and  the  maintenance  of  hospitals  and 
of  orphan  asylums. 

195-  Heredity  of  Disease. — The  term  heredity  of  disease 
is  one  which  has  been  misunderstood  by  many  people. 
By  the  term  heredity  we  mean  that  which  is  handed  on 
from  parents  to  their  offspring.  In  the  case  of  biological 
diseases  which  are  caused  by  some  definite'  plant  or  animal, 
it  is  evident  that  they  cannot  be  inherited.  But  when  t la- 
parents  are  afflicted  with  a  biological  disease,  their  bodii is 
become  weakened  and  their  offspring  may  have  a  poor 
constitution  so  that  they  are  more  easily  affected  by  disease. 

196.  Immunity.  —  Immunity  is  a  technical  term  which 
means  that  the  body  resists  or  is  not  susceptible  to  the 
germs  of  biological  diseases.  Many  people  do  not  become 
sick  when  there  is  an  epidemic  of  typhoid  fever,  measles, 
malaria,  or  the  like.  Such  people  are  said  to  possess  a 
high  degree  of  natural  immunity  to  disease  germs.  People 
usually  well  frequently  take  germ  diseases  when  the  body 
happens  to  be  exhausted  by  care  or  work.  In  such  cases 
the  immunity  of  the  body  has  been  weakened.  Many  of 
the  germ  diseases  confer  immunity  against  a  second  attack 
of  the  same  disease,  but  tins  does  not  hold  true  for  all 
persons  or  for  all  germ  diseases.  Vaccination  a  gain  si 
smallpox,  in  the  case  of  most  persons,  confers  immunity 
for  about  seven  years.  Inoculation  with  the  typhoid 
serum  confers  immunity  for  from  two  to  three  years.  Im- 
munity, then,  is  a  relative  term,  and  depends  in  a  large 
measure  on  the  state  of  health  of  the  individual  and  on 
his  power  of  resisting  the  poisonous  effects  of  disease 
germs. 


256 


THE  BIOLOGY  OF  DISEASE 


Student  Report 


Due  to  Some  Plant 

or  Animal 

Treatment  by 

Prevented 

BY 

4J 

a> 

s 

In  the  watei 

o 

C3 

3 
o 

s 
5 

u 

to 

CD 

3 

"3 

<33 
C 

O 

^— 
eS 

O 
■ji 

<o 
P* 

a) 

5* 

bo 

"c 
pq 

_o 

C5 

— * 

5 
to 

CO 

o 

SB 

B 

5 

Cold      .... 

X 

X 

X 

X 

X 

Measles      .     .     . 

Whooping  cough 

* 

• 

Typhoid  fever     . 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

Tuberculosis   .     . 

Add  others      .     . 

197.  What  are  you  going  to  do  and  how  are  you  going  to 
do  it  ? —  We  have  now  learned  some  of  the  facts  about 
how  to  keep  well  and  how  to  do  our  life  work  effectively 
and  efficiently.  We  all  begin  life  as  children  with  an  un- 
known work  to  do.  How  well  are  we  going  to  do  it  ? 
Judge  Lindsay  says,  "  Children  are  the  life  blood  of  the 
states.  They  are  better  producers  of  energy  than  steam 
or  electricity."  Davenport  in  a  new  study  emphasizes 
this  point  in  the  following  words:  "The  human  babies 
born  each  year  constitute  the  world's  most  valuable  crop. 
Taking  the  population  of  the  globe  to  be  one  and  one- half 
billion,  probably  about  fifty  million  children  are  born  each 
year.  In  the  continental  United  States  with  over  ninety 
million  souls  probably  two  and  one-half  million  children 
are  annually  born.  When  we  think  of  the  influence  of  a 
Harriman,  of  an  Edison,  of  a  William  James,  the  potential- 
ity is  far  from  being  realized.  Nearly  half  a  million  of 
these  infants  die  before  they  attain  the  age  of  one  year, 
and  half  of  all  are  dead  before  they  reach  their  23d  year 


WHAT  ARE    YOU  GOING   TO   DO  257 

—  before  they  have  had  much  chance  to  affect  the  world 
one  way  or  another.  However,  were  only  one  and  a 
quarter  million  of  the  children  born  each  year  in  the 
United  States  destined  to  play  an  important  part  for  the 
nation  and  humanity  we  could  look  with  equanimity  on 
the  result.  But  alas!  only  a  small  part  of  this  army  will 
be  fully  effective  in  rendering  productive  our  three  million 
square  miles  of  territory,  in  otherwise  utilizing  the  un- 
paralleled natural  resources  of  the  country,  and  in  foi  ming 
a  united,  altruistic,  God-fearing,  law-abiding,  effective  and 
productive  nation.  On  the  contrary,  of  the  1,200,000  who 
reach  full  maturity  each  year,  forty  thousand  will  be 
ineffectual  through  temporary  sickness,  four  to  live  thou- 
sand will  be  segregated  (placed  apart)  in  the  care  of 
institutions,  unknown  thousands  will  be  kept  in  poverty 
through  mental  inefficiency,  other  thousands  will  be  the 
cause  of  social  disorder,  and  still  other  thousands  will  be 
required  to  attend  and  control  the  weak  and  unruly.  We 
may  estimate  at  not  far  from  100,000,  or  eight  per  cent, 
the  number  of  the  non-productive  or  only  slightly  pro- 
ductive, and  probably  this  proportion  would  hold  for  the 
600,000  males  considered  by  themselves.  The  great  mass 
of  the  yearly  increase,  say  550,000  males,  constitute  a 
body  of  solid,  intelligent  workers  of  one  class  and  another. 
engaged  in  occupations  that  require,  in  the  different  cast  s, 
various  degrees  of  intelligence  but  are  none  the  less  valu- 
able to  the  progress  of  humanity.  Of  course,  in  these 
gainful  occupations  the  men  are  assisted  by  a  Large  num- 
ber of  their  sisters,  but  four-fifths  of  the  women  are  still 
engaged  in  the  no  less  useful  work  of  home-making. 

"It  is  a  reproach  to  our  intelligence  that  we  as  a  people, 
proud  in  other  respects  of  our  control  of  nature,  should 
have  to  support  about  half  a  million  insane,  feeble-minded, 
epileptic,  blind,  and   deaf,   80,000  prisoners,  and    100,000 


258  THE  BIOLOGY  OF  DISEASE 

paupers  at  a  cost  of  over  one  hundred  million  dollars  per 
year."  — Davenport. 

SUMMARY 

Disease  prevents  us  from  working  as  we  do  when  we 
are  well.  Most  diseases  are  unnecessary  and  preventable, 
especially  all  which  are  caused  by  some  plant  or  animal  liv- 
ing as  a  parasite  in  our  bodies.  In  most  of  the  biological 
diseases  some  definite  poison  produced  by  the  parasite  is 
taken  into  the  body,  and  this  is  the  chief  cause  of  the  disease. 
As  a  physician  knows  the  nature  of  a  disease  and  its  effect 
upon  the  body,  he  can  aid  materially  in  overcoming  the 
illness.  Each  biological  disease  is  distinct  and  must 
have  special  treatment.  Many  of  these  diseases  are  taken 
from  some  one  who  has  the  disease.  Vaccination,  quaran- 
tine, and  disinfection  are  measures  which  help  to  prevent 
the  spread  of  germ  diseases.  It  is  our  duty  to  keep  well, 
and  we  can  do  much  toward  this  by  understanding  how 
to  avoid  the  biological  diseases. 

QUESTIONS 

What  are  the  biological  diseases  ?  How  many  biological  diseases  do 
you  know  ?  Name  them.  Describe  a  germ  disease.  Describe  malaria. 
What  is  vaccination  ?  What  is  quarantine  ?  For  what  diseases  are 
people  quarantined  ?  What  is  the  work  of  the  Board  of  Health  ?  What 
is  the  purpose  of  disinfection  ?     What  are  the  chief  disinfectants  ? 

REFERENCES 
Celli-Eyre,  Malaria. 

Chalmers,  The  Beloved  Physician  Edward  L.  Trudeau. 
Chapin,  Sources  and  Modes  of  Infection. 
Conn,  Bacteria  in  Milk. 

Cornell,  Health  and  Medical  Inspection  of  School  Children. 
Edelman,  Mehler  &  Eichorn,  Meat  Inspection. 
Knoff,  Tuberculosis,  A  Preventable  and  Curable  Disease. 
Rosenau,  Disinfection  and  Disinfectants. 
Stiles,  Prevalence  and  Geographical  Distribution  of  Hookworm  Disease 

Hygienic  Laboratory,  Bulletin  Number  10,  Washington. 
Trudeau,  Edward  L.,  An  Autobiography. 


PART   III 


PLANT   BIOLOGY 


CHAPTER    XX 


TYPICAL   FLOWEKING   PLANTS 

198.  Introduction.  —  The  study  of  plant  biology  may 
begin  with  any  plant.  The  trees  in  the  park,  the  grass  in 
the  lawn,  and  the  hothouse 

geranium,  all  respire,  use 
food,  and  grow.  These 
are  plant  life  processes, 
and  they  are  similar  to 
the  same  life  processes  in 
animals. 

199.  The  Bean  Plant.  — 
We  begin  the  study  of 
plants  with  the  bean,  be- 
cause it  can  be  grown  in 
the  laboratory  with  little 
care  and  because  its  parts 
are  easy  to  examine.  The 
whole  bean  plant,  Figure 
252,  is  made  up  of  many 
parts,  the  roots  which 
hold  the  plant  in  the 
ground  and  absorb  water, 


Figure  252.  —  Bean  Plant. 
For  root  details  see  Figure  261. 


•j.v.i 


260 


TYPICAL   FLOWERING  PLANTS 


Figure  253.  —  Photograph  of  Bean 
and  Pea. 


and   the    stem    which   supports   the    leaves,   flowers,  and 

pods.     Each  of  these  parts  is  called  an  organ,  and  each 

does  a  given  work.     While  we  are  learning  how  the  bean 

uses  these  organs,  we 
shall  compare  them  with 
similar  organs  in  other 
flowering  plants,  and  in 
this  way  come  to  under- 
stand how  all  plants  of 
this  kind  live. 

200.  The  Bean  Seed.  — 
The  bean  seed  discussed 
in  this  study  is  the 
familiar  dry  bean,  white 
or   red   in    color.     This 

seed  contains  the  embryo  or  young  plant  which  consists 

of    three    important  parts,  all   inclosed  in  the  seed  coat 

(testa).       These    parts    are  :     (1)    the 

small  stem,  the  hypocotyl  (hy-po-kotpl: 

Greek,  hypo,  beneath  ;   kotyle,  cavity) ; 

(2)  the  seed  bud,  the  plumule  (plum'ul  : 

Latin,  plumula,  feather);   (3)  the  seed 

leaves,    the     cotyledons     (kot-y-le'don: 

Greek,  kotyledon,  socket).     See  Figures 

253  and  254. 

Every  bean  is  attached  at  a  definite 

point  to  the  pod  in  which  it  grows,  and 

a  scar,  called  the  hilum  (hl'lum:    Latin, 

hilum,  a  little  body),  shows  where  the     Compare  with  Figure 

point  of  attachment  was.     Through  this 

hilum  enters  all  the  food  material  which  makes  the  bean 

seed.     The  testa  or  coat  of   the   bean  is  the  hard  outer 

layer,  and  beneath  this  may  sometimes  be  seen  a  delicate 

inner  layer,   called  integument     These  two  layers  of  the 


P  3phe 


Micropyle 


Plumule 


Hilum 


JAJ     /''Testa 
Cotyledon 


Figure  254.  —  Parts 
of  Bean  Seed. 


THE  BEAN  SEED  261 

seed  coat  protect  the  young  bean  embryo.  Other  mark- 
ings on  the  outside  of  the  bean  are  the  micropyle 
(mi'kro-pil:  Greek,  micro,  small;  pyle,  gate),  a  small  dol 
at  one  end  of  the  hilum,  and  the  raphe  (ra'fe:  Greek, 
raphe,  a  seam),  a  band  or  ridge  which  extends  Lengthwi 
around  the  bean  from  the  top  of  the  hilum  tu  the  bottom. 

The  small  stem  or  hypocotol  is  the  part  of  the  bean 
embryo  that  first  escapes  from  the  seed  coat  when  tin- 
young  bean  begins  to  grow.  One  end  of  this  small  stem 
soon  develops  into  a  root  which  grows  into  the  groin  id. 
and  the  other  end  develops  into  a  stem  which  grows 
above  the  ground  and  lifts  the  seed  leaves  into  the  light. 

The  seed  leaves  or  cotyledons  are  by  far  the  largest 
part  of  the  bean,  and  their  size  is  due  to  the  great  amount 
of  food  stored  in  them.  They  are  the  parts  of  tin-  bean 
seed  which  are  important  to  man  and  animals  as  food. 

The  seed  bud  or  plumule  consists  of  two  small  Leaves. 
The  plumule  is  connected  closely  with  the  food  stored  in 
the  seed  leaves,  which  is  taken  up  by  the  young  plant 
and  used  in  growing. 

LABORATORY   STUDY 

Place  a  few  beans  in  dry  sand  in  a  warm  room.  Why  do  not  the 
beans  grow  and  sprout?  Place  others  in  water  in  a  warm  room.  What 
happens  ?  Place  other  beans  in  moist  earth  (a)  in  a  warm  room  ;  M  in 
a  cool  place.  Examine  in  a  few  days.  These  several  experiments  show 
the  influence  of  temperatures,  soil,  and  moisture  on  the  sprout  in g  of  beana 
Heat  a  few  beans  in  an  oven  for  ten  minutes  and  then  place  them  in  a 
warm,  moist  soil.  Why  do  they  not  grow?  Soak  beans  for  several 
hours.  Remove  the  testa  and  place  them  beside  dry  beans  for  a  to- 
days. What  happens  ?  This  experiment  illustrates  one  use  <<t  the  testa. 
Examine  a  dry  bean.  Split  it  along  the  bark  and  observe  I)  the  two 
parts  into  which  it  divides.  These  are  the  cotyledons  of  the  new  plant. 
Note  (2)  the  pair  of  small  white  leaves  which  are  the  plumule  <>t  the  new 
plant;  (3)  the  hypocotyl,  below  the  cotyledons,  from  which  the  stem 
and  roots  will  grow;  (4)  the  hard  covering  or  testa.  Look  for  the 
micropyle  and  raphe  on  a  bean  not  split. 


262 


TYPICAL   FLOWERING   PLANTS 


Figure  255.  —  Diagram 
of  Corn  Seed. 


201.  Corn  -'Seed.''  —  A  grain  or  kernel  of  corn,  com- 
monly called  a  seed,  is  like  a  bean  (1)  in  containing  a 
young  plant,  the  corn  embryo  ;  (2)  in  containing  food 
for  the  use  of  the  embryo  when  it  first  begins  to  grow ; 

and  (3)  in  having  marks  upon  it. 
On  the  top  of  the  kernel  is  a  slight 
prominence,  the  scar  which  marks  the 
place  where  one  thread  of  the  so- 
called  silk  was  attached.  On  one 
side  of  the  kernel  is  a  depression 
beneath  which  the  embryo  lies,  and 
at  the  base  is  a  stalk  by  which  the 
kernel  is  attached  to  the  cob  during 
its  development  (Figure  255). 

A  corn  grain  differs  from  a  bean  in 
being  a  fruit,  —  that  is,  the  seed  case 
adheres  to  the  seed  coat  as  a  second 
covering.  A  kernel  of  corn,  therefore,  corresponds  to  a  bean 
pod  containing  but  one  seed.  Corn  differs  from  the  bean 
also  in  the  position  of  the  embryo,  which  is  at  one  side  of  the 
food  supply.  The 
latter  is  called  the 
endosperm  (en' do- 
sperm  :  Greek,  endo, 
within  ;  sperma,  a 
seed).  Another  dif- 
ference between  the 
two  is  that  the  corn 

has  a  single  modified  cotyledon  called  the  scutellum  (sku- 
tel'lum  :  Latin,  diminutive  of  scutum,  a  shield),  the 
use  of  which  is  to  absorb  and  digest  the  food  and  carry 
it  to  the  embryo  (Figure  255).  The  cotyledon  of  the 
corn  never  appears  above  ground.  The  corn  embryo  has 
its  leaves  rolled  into  a  tight,  pointed  bud,  which  enables 


Figure  256.  —  Sun- 
flower "  Seed." 

A  fruit. 


Figure   257.  — ■ 
Squash  Seed. 


CLASSIFICATIOX   OF    SEEDS 


263 


it  easily  to  pierce  the  earth  above.     The  root  is  at  the 
lower  part  of  a  short  hypocotyl. 

As  the  corn  has  but  one  cotyledon,  it  belongs  to  the 
class  of  plants  known  as  monocotyledons  (moii-o-kot-v-lr'- 
don  :  Greek,  mono,  one  ;  kotyledon,  socket).  The  bean, 
having  two  cotyledons,  belongs  to  the  class  dicotyledon* 
(di-kot-y-leMon  :   Greek  di,  two  ;   kotyledon,  socket). 

LABORATORY  STUDY  WITH  CORN 

Remove  most  of  the  endosperm  from  a  few  kernels,  and  plant  them. 
How  does  the  growth  compare  with  that  of  a  kernel  retaining  ;ill  its 
endosperm?  Examine  whole  corn  kernels,  noting  (1)  silk  sear  on  top  ; 
(2)  depression  on  the  side  ;  (3)  hard  outer  covering;  (4)  stalk  by  which 
it  was  attached.  Cut  crosswise  a  kernel  which  has  been  soaked  in  wal 
and  identify  the  embryo,  scutellum,  endosperm,  and  hard  outer  covering. 
Split  a  kernel  lengthwise  and  find  the  same  parts.  Remove  the  embryo 
from  another  soaked  kernel  and  study  its  attachment  to  the  endosperm. 
Look  for  the  plumule  and  root. 

Examine  such  seeds  as  you  can  obtain  and  make  a  report,  using  the 
following  table  as  guide. 


Bean  . 
Pea      . 

Corn  . 
Squash 
Etc.      . 


Size 


Embryo 

EASILY 

Seen 


IIili  M    AT 
BlDH 


llll.t  M    OS 

End 


Two 

COTJ  i.l  - 
DONS 


■  '■  B 
COTYl  K- 

|..,N 


202.  Classification  of  Seeds.  —  The  comparative  stud\  oi 
the  bean  and  corn  seeds  shows  the  important  parts  of  seeds 
and  explains  the  chief  differences  between  them.  The 
common  seeds  are  classified  as  follows :  monocotyledons: 
grass,  wheat,  barley,  oats,  and  rye  ;  dicotyledons  :  Bquash, 
morning  glory,  tomato,  radish,  and  beet. 


264 


TYPICAL   FLOWERING   PLANTS 


203.  Growth  of  the  Bean  Embryo.  —  As  soon  as  the  ground 
is  warm  in  the  spring,  farmers  plant  beans  in  rows.  After 
the  bean  seed  has  lain  in  the  damp  earth  for  about  ten  days, 
the  moisture  has  softened  the  seed  coat  and  food,  and  the 
shoots  from  the  beans  begin  to  show  above  the  ground. 

The  first  part  of  the  bean  embryo  to  show  is  grown  in  the 
little  stem  (hypocotyl).  This  curves  sharply  into  an  arch 
and  begins  to  push  upward  through  the  particles  of  soil.    At 

the  same  time  delicate 
roots  push  downward 
into  the  soil  (Figure 
258).  As  soon  as  the 
arch  of  the  hypocotyl 
has  pushed  through  the 
soil  into  the  light,  it 
straightens  up  and  pulls 
the  seed  leaves  (coty- 
ledons) out  of  the 
ground.  The  seed  coats 
are  usually  left  behind 
in  the  soil.  As  soon  as  the  cotyledons  are  exposed  to  the 
light,  they  crack  apart,  slowly  spread  wide  open,  and  in  a 
few  days  become  green.  During  these  changes  in  the  coty- 
ledons, the  leaves  of  the  plumule  have  taken  from  them 
the  food  stored  for  the  use  of  the  growing  bean  embryo. 
As  soon  as  this  store  of  food  is  absorbed  by  the  young 
bean  plant,  the  cotyledons  drop  to  the  ground.  The  bean 
seedling  is  no  longer  dependent  on  the  food  in  the  seed, 
but  is  able  to  gain  its  food  from  the  soil  and  air. 

During  the  summer  the  bean  plant  grows  bean  seeds, 
and  the  farmers  harvest  the  beans  and  store  the  seeds  in 
barrels,  sacks,  or  wooden  bins.  The  dry  beans  may  be 
kept  for  years  and  still  grow  bean  plants  at  any  time 
when  conditions  are  favorable. 


a 


Figure  258.  —  Germination  of  Bean. 


FOODSTUFFS  IN   THE  BEAN 


2IW3 


LABORATORY   STUDY 

Examine  germinating  seeds  and  young  seedlings  »>f  various  kind 

plants,  and  note  their  peculiarities  in  Bprouting  as  indicated  below. 


Bean  . 
Corn  . 
Pea     . 

Tomato 
Squash 
Maple 
Etc.     . 


Ai:<  ii 

Pkominent 


Ai;i  li    HOI 

l'l'.i'MIMN  I 


Cotyledons 

\  BOVK 
(  litoi  N l> 


COTYLl  l>>'S^ 

ttO  I      A  l«i\  I 

< .  BOUND 


I  i  -  i  \ 

Brocohi    I  P 


204.  Foodstuffs  in  the  Bean.  —  The  bean  stores  two  kinds 
of  stuffs:  carbohydrates  and  proteins.  Carbohydrate  is 
the  name  of  the  foodstuff  which  includes  such  foods  as 
sugar  and  starch.  The  term  protein  is  applied  to  the 
foodstuff  found  in  such  foods  as  the  lean  of  meat,  the  white 
of  egg,  and  the  curd  of  milk  which  we  use  as  cheese. 

The  presence  of  these  foodstuffs  may  be  shown  by 
applying  the  following  chemical  tests.  I  >oil  beans  until 
they  are  soft  and  then  place  a  small  portion  of  them  in  a 
test  tube.  Add  a  drop  of  iodine.  If  starch  is  present, 
the  mixture  will  turn  purple  in  color.  Add  strong  nitric 
acid  to  a  second  portion  in  a  clean  test  tube,  boil  and 
cool.  If  protein  is  present,  the  mixture  will  be  a  clear 
yellow  color  which  will  become  orange  if  ammonia  is 
added.      To  a  third  portion  add   Fehling's1  solution  as  a 


i       1.  Copper  sulphate 9  grams 

Water 500cc. 

2.   Rochelle  salts 49  ,i;r;iiii> 

Caustic  potash 30  grams 

Water 250cc. 

Take  two  volumes  of  l.  and  one  of  2,  and  add  to  the  mixture  2  rolum< 
water.    Do  not  mix  1  and  2  until  ready  to  use. 


266 


TYPICAL  FLOWERING  PLANTS 


test  for  sugar.  If  the  latter  is  present,  the  mixture  will 
become  dull  orange  when  heated.  Test  uncooked  seed  for 
oil  (1)  by  heating  it  over  a  lamp  on  a  sheet  of  linen  paper  ; 
(2)  by  soaking  it  over  night  in  ether.  (This  must  not  be 
near  a  flame  at  any  time.)  If  oil  is  present,  it  will  show 
on  the  paper  as  a  clear  spot,  and  in  the  second  test  the 
oil  will  appear  on  the  surface  of  the  ether  in  the  test 
tube. 

Make  a  record  of  the  results  as  indicated  below: 


• 

Much 
Peotein 

Much 
Staech 

Oil 

SUGAB 

Bean 

Corn 

Wheat     .... 

Walnut  .... 

Pea 

• 

205.  Digestion  of  the  Food  in  the  Seed.  —  It  may  appear 
strange  that  the  growing  bean  plant  lives  upon  the  food 
stored  in  the  cotyledons,  and  yet  such  is  the  case.  But  this 
food  must  undergo  a  real  digestion  before  the  bean  embryo 
can  use  it.  We  do  not  know  just  how  this  digestion  takes 
place  in  the  bean,  but  in  the  corn,  as  we  have  learned, 
there  is  a  special  structure,  the  scutellum,  which  helps  to 
digest  the  food  in  the  endosperm.  This  corn  scutellum 
may  be  removed  from  the  corn  seed  and  made  to  digest 
other  kinds  of  starch,  for  instance,  that  obtained  from  a 
finely  grated  potato.  This  should  be  kept  warm  and 
moist  for  several  hours,  after  which  it  may  be  tested  for 
sugar  with  Fehling's  solution  (See  page  265).  When 
scientists  learn  more  about  the  digestive  processes  of 
plants  they  will  probably  find  that  they  are  similar  to 
the  digestive  processes  of  animals. 


ROOT  SYSTEM 


2(37 


206.  The  Bean  Seedling  —  Each  bean  seedling  is  provided 

with  a  supply  of  food  which  gives  it  a  start  in  life.  But 
after  this  supply  is  exhausted,  the  young  beao  must  be 
able  to  prepare  its  own  food.  The  Beveral  parts  of  the 
bean  seedling  are  the  roots,  stem,  and  leaves,  all  of  which 
work  in  preparing  the  seedling's  food. 

207.  Root  System.  —  The  first  root  to  form  on  the  bean 
is  called  the  tap  or  primary  root  and  grows  straight 
downward.  Many 
branches,  known  as 
secondary  roots,  grow 
from  the  taproot. 
These  large  secondary 
roots  serve  chiefly  to 
hold  the  plant  firmly 
in  place.  From  the 
secondary  roots  smaller 
branches  or  rootlets 
grow,  and  on  these,  a 
short  distance  back 
from  the  tip,  are  nu- 
merous root  hairs. 

In  order  to  under- 
stand the  other  great 
use  of  roots,  we  must 
be  familiar  with  their 
structure.    A  cross  sec- 


Figure  259.  —  Bean  Plants. 

All  the  food  these  plants  have  used  came 
from  the  cotyledons,  as  the  jar  contained 
only  sawdust. 


tion  of  a  taproot  shows  three  regions.  In  the  central  part 
is  a  woody  portion  called  the  central  cylinder.  Next  i«>  and 
outside  of  this  is  a  layer  known  as  the  endoderm  (Greek, 
endo,  within  ;  derm,  skin)  which  separates  tin-  central 
cylinder  from  the  next  region,  the  cortex  (hat in,  cortex, 
bark).  Outside  of  all  is  a  thin  protective  layer,  the 
epidermis. 


268 


TYPICAL  FLOWERING  PLANTS 


If  we  examine  under  the  microscope  a  portion  of  the 
epidermis  taken  from  near  the  center  of  an  onion  bulb,  we 

find  that  it  is  made  up  of  many 
small  parts,  called  cells.  Every 
cell  consists  of  living  matter 
(protoplasm)  surrounded  by  a 
wall.  Near  the  center  of  each 
cell  is  a  small  spherical  body 
called  the  nucleus.  See  page  4. 
All  regions  of  the  plant  body 
are  made  of  such  cells,  and  the 
cells  of  each  region  are  adapted 
to  the  special  work  of  that  re- 

f-v^^^Sii^^i^^^S  sdon.     Therefore  the  cells  of  a 

3miVfB  plant   body   vary  in   size    and 

shape,  but  all  the  cells  of  any 
one  region  are  nearly  alike. 
Such  a  group  of  similar  cells 
is  called  a  tissue.  See  page  5. 
A  cross  section  of  a  taproot 
shows  the  tissues  of  all  the 
layers  in  the  plant.  The  cen- 
tral cylinder  contains  groups 
of  cells  called  fibrovascular 
bundles.  Some  of  these  cells 
overlap  in  such  a  way  that  they 
make  continuous  tubes  from 
the  root,  up  through  the  stem, 
and  into  the  leaves.  In  the 
leaves  the  vascular  bundles  are 
called  veins.  The  cells  which 
carry  the  liquids  present  in  the  plant  are  to  the  plant 
what  veins  and  arteries  are  to  animals.  The  inner  part 
of  a  vascular  bundle  is  made  up  of  woody  cells  and  is 


Figure  260.  —  Sections  of 
Bean  Root. 

1,  epidermis;  2,  cortex; 
3,  central  cylinder. 


ROOT  SYSTEM 


269 


nucleus- 


epidermal 
celiacs 


Figure  261.  —  Root  Hairs. 


called  the  xylem.  These  cells  carry  water  from  the  root 
upwards.  The  outer  part  of  the  bundle  (the  phlo&m) 
is  of  a  softer  tissue  and  contains  the  sieve  vessels  which 
carry  liquid  food  downward. 

The  epidermis  of  the  rootlets  is  covered  with  rout 
hairs,  which  are  really  much  elongated  cells  (Figure  261). 
While  root  hairs  help  to 
hold  a  plant  firmly  in 
place,  their  main  use  is 
to  take  up  water  from 
the  soil.  The  cell  walls 
are  thin  and  are  lined 
with  a  thin  layer  of  pro- 
toplasm. Water  is  taken 
in  through  the  walls  of  the  cells  by  osmosis  (page  3).  The 
root  hairs  which  grow  in  soil  apply  themselves  closely  to 
particles  of  it,  and  take  from  them  the  thin  film  of  water 
with  which  each  is  covered.      On  this  account  the  hairs  or 

rootlets  grown  in  soil  are  much  more 
irregular  in  shape  than  those  grown  in 
water  or  in  moist  air.  Unless  a  plant  is 
removed  carefully,  all  the  root  hairs  are 
broken  off  and  remain  in  the  ground. 

Another  statement  is  frequently 
made  in  discussing  the  uses  of  rout 
hairs,  namely,  that  by  means  of  an 
acid  which  they  secrete,  they  dissolve 
minerals  in  the  soil  so  that  they  can 
be  taken  up  by  water  and  carried  into 
the  plant.  This  is  based  on  the  fact  that  a  seedling 
grown  on  a  polished  marble  plate  will  corrode  the  sur- 
face, and  on  other  experiments.  Researches  recently 
made  prove  conclusively  that  root  hairs  do  nut  secrete 
acid. 


Figure  262. 
Cap. 


Root 


270 


TYPICAL   FLOWERING   PLANTS 


Rootlets  are  protected  on  the  end  by  a  structure  called 
a  root  cap  (Figure  262).  This  cap  is  made  up  of  loose  cells 
which  are  constantly  formed  from  the  inside.  As  fast  as 
the  outer  cells  are  destroyed  by  the  pushing  of  the  root 
through  the  soil,  new  cells  are  ready  to  take  their  place. 

Small  bunches,  called 
tubercles  (Figure  263)  are 
found  on  the  rootlets 
of  plants  of  the  bean 
family.  The  tubercles 
are  filled  with  bacteria 
which  gather  nitrogen 
from  the  air,  use  what 
they  need,  and  leave  the 
surplus  in  the  roots. 
Some  of  this  nitrogen 
is  used  by  the  growing 
plants  themselves,  and 
any  that  they  do  not  use 
is  left  in  the  soil  for  the 
use  of  other  plants. 
Most  plants  take  from 
the  soil  more  nitrogen 
than  they  add  to  it,  but 
the  opposite  is  the  case 
with  beans  and  their 
relatives.  Thus  clover  and  other  relatives  of  the  bean 
are  used  by  farmers  as  a  cover  crop  or  for  "green 
manure,"  so  called,  for  the  sake  of  replacing  in  the 
soil  the  nitrogen  which  other  crops  have  used  up.  The 
practice  of  rotating  crops  depends  on  the  fact  that  dif- 
ferent kinds  of  plants  use  different  material  in  the  soil.  In 
successive  years  crops  of  different  kinds  will  grow  better 
than  crops  of  the  same  kind,  unless  the  soil  has  been  sup- 


Figure  263.  —  Bean  Roots. 
Showing  tubercles. 


THE    lU.AX    STEM 


271 


Figure  264.  —  Fibrous  Roots  of 
Buttercup. 

How  do  they  differ  from  the  bean  roots  ? 


plied  with  the  used-up  ele- 
ments through  the  aid  of 
fertilizers  and  chemicals. 

When  water  containing 
minerals  in  solution  is 
taken  in  through  the  root 
hairs,  it  is  passed  along 
by  osmosis  to  the  woody 
layer  of  the  rootlets  and 
thence  to  the  primary  root 
from  which"  it  is  distrib- 
uted to  the  parts  of  the 
plant  above  ground.  Here 
it  is  made  into  food  and 
carried  by  the  phloem  of 
the  vascular  bundle  to 
all  parts  of  the  plant. 

The  root  system  of  a  plant,  then,  serves  two  main  purposes  : 
to  hold  it  fast  in  the  ground,  and  to  absorb  water  from  tin- 
earth.  In  passing  through  the  soil  this  water  has  taken  up 
mineral  substances  which  will  enter  into  the  plant's  food. 

LABORATORY   STUDY   OF   ROOTS 

Cut  a  carrot  crosswise  and  lengthwise,  and  note  the  centra]  cylinder 
and  cortex.  Cut  across  one  of  the  larger  bean  roots,  noting  (1)  the  cen- 
tral woody  cylinder ;  (2)  the  softer  ring  surrounding  it;  (3)  the  outer 
epidermis.  Cut  a  root  lengthwise  and  find  the  same  tissues.  Examine 
sprouted  barley  for  root  hairs  and  root  caps;  also  a  radish  seedling  for 
root  hairs.  Stand  a  cut-off  root  in  red  ink  for  a  few  hours.  Make  a 
and  lengthwise  sections,  noting  what  part  has  been  stained  by  the  ink. 
This  shows  the  routes  through  which  absorbed  water  travels. 

208.  The  Bean  Stem.  —  The  bean  stem  is  made  up  of  three 
parts  :  (1)  a  central  pith  where  food  is  stored  ;  (2)  woody 
fiber  which  conducts  water;  and  (3)  a  bark  and  an  epidermis 
which  cover  and  protect  it.     The  stem  aa  a  whole  holds  up 


272  TYPICAL  FLOWERING  PLANTS 

the  leaves  to  the  air  and  light,  carries  water  and  food 
materials  gathered  by  the  roots  to  the  leaves,  and  distributes 
liquid  foods  to  all  parts  of  the  plant. 

LABORATORY   STUDY   OF  A   BEAN   STEM 

Make  a  cross  section  of  a  bean  stem  and  find  (a)  the  central  pith; 
(b)  the  woody  ring  surrounding  it;  and  (c)  the  outer  green  bark  and  the 
epidermis.  Split  a  stem  lengthwise  and  identify  these  parts.  Stand  the 
cut-off  end  of  a  stem  in  red  ink  for  a  few  hours ;  then  cut  across  and 
lengthwise,  noting  that  the  woody  tissue  is  stained  red.  Compare  the 
stem  with  the  root. 

209.  The  Bean  Leaves.  —  A  bean  leaf  consists  of  two 
parts  :  the  stalk  or  petiole  (Latin,  petiolus,  fruit  stalk)  by 
which  it  is  attached  to  the  stem,  and  the  broad,  green  part, 
the  blade.  Petioles  are  longer  in  some  parts  of  the  plant 
than  in  others.  Where  are  the  longest  ones  ?  What 
reason  can  you  give  for  this? 

The  blade  of  a  leaf  is  in  three  parts,  each  of  which  has 
a  prominent  rib  entering  it  from  the  petiole.  From  the 
rib  many  small  branches  extend  to  all  parts  of  that  division 
of  the  blade.  The  vascular  bundles,  or  veins,  are  of  use 
to  the  leaf,  not  only  in  carrying  water  to  it  from  the  root 
and  food  back  to  the  root  from  the  leaves,  but  also  in  giving 
firm  support  to  the  soft  parts  between  them. 

A  leaf  like  the  bean,  which  has  many  small  veins  running 
together,  is  called  a  net-veined  leaf.  All  dicotyledonous 
plants  have  leaves  with  net  veins. 

A  section  through  the  blade  of  a  leaf  shows  several  dis- 
tinct parts  (Figure  265).  The  outermost  layer  is  the  epi- 
dermis, a  layer  of  cells  without  much  color,  which  serves 
as  a  protective  skin.  Below  the  epidermis  is  a  layer  of 
brick-shaped  cells  placed  on  end.  These  are  called  the 
palisade  cells.  They  contain  green  coloring  matter  (chloro- 
phyll) which  is  held  in  small  bodies  called  chloroplasts,  a 


THE   BEAN   LEAVES 


273 


word  meaning  color-bearers.     The  position  of  the  palisade 

cells  makes  the  upper  surface:  of  the  Leaf  firmer  than  it 
would  otherwise  be.     The  arrangement  of  the   cells  in  a 

compact  layer  regulates  the  amount  of  light  that  penetrates 
to  the  interior  of  the 
leaf  and  helps  to  pre- 
vent undue  loss  of  water. 
Below  the  palisade  cells 
are  the  loosely  arranged 
cells  of  a  spongy  layer. 
They  contain  chlorophyll  d! 
and  are  exposed  to  the 


oooooooo 


spongy  layer 
chlorophyll 


lower  epiaer  mis 


•stoma 


air  which  enters  through      Figure  265.  — Cross  Siction  of  Bean 

i 
the  holes   in   the    lower  F* 

epidermis.     Most  of  the  How  many  tissues  present  ? 

work  of  the  leaf  is  done  in  this  green  tissue.  Because 
this  tissue  lies  in  the  middle  of  the  leaf,  it  is  known  as 
mesophyll  (mez'o-fll:   Greek,  mesos,  middle  ;  phyllos,  leaf). 

The  holes  {stomata)  in  the  lower  epi- 
dermis are  more  than  mere  holes,  for  they 
can  become  larger  or  smaller  according 
to  the  needs  of  the  plant.  Seen  from  tin- 
surface,  each  stoma  is  surrounded  by  two 
bean-shaped  cells,  containing  some  chloro- 
phyll. These  cells  (Figure  -''>")  called 
guard  cells,  have  the  power  of  absorbing 
water  to  a  greater  degree  than  the  other 
cells  of  the  epidermis.  When  the  guard 
cells  are  full  of  water,  or  turgid,  the 
Opening  between  them  is  larger  than 
when  they  are  almost  empty  or  flaccid.  The  size  of  the 
openings  regulates  the  amount  of  air  which  passes  in  and 
out,  and  of  the  watery  vapor  which  passes  out. 

The  stomata  are  more  numerous  on  the   under   side  of 


Figure  266.  —  Leaf 
Skeleton. 

Showing  net  veins. 


274 


TYPICAL  FLOWERING  PLANTS 


cells  of 
epidermis 

'---stoma 


gu-^rd  cell 


Figure  267.  —  Epidermis 
of  Leaf. 


leaves  which  grow  with  the  blades  in  a  horizontal  position, 
because  there  the  stomata  are  protected  from  water  which 
would  interfere  with  their  action.  Leaves  which  are 
nearly  upright  have  the  stomata  on  both  sides,  and  leaves 
like  a  water  lily  that  rest  on  the  surface  of  the  water  have 
the  stomata  on  the  upper  surface.     Stomata  are  both  small 

and  numerous.     A  dozen  or  more 
are  found  in  some  leaves  in  a  circle 
no  larger  than  a  period  on  this 
page. 

During  a  season  a  large  amount 
of  water  passes  off  through  the 
stomata  of  any  plant.  The  pro- 
cess of  giving  off  this  water  is 
called  transpiration.  This  pro- 
cess is  unavoidable.  The  root  hairs  gather  water  almost  con- 
tinuously, and  this  is  carried  to  the  leaf  by  the  fibrovascular 
bundles  and  distributed  to  the  cells.  The  mesophyll  in 
the  leaf  uses  the  minerals  which  the  water  contains,  but 
it  does  not  use  all  of  the  water.  This  excess  is  cast  off 
into  the  spaces  between  the  cells  (intercellular  spaces), 
which  communicate  with  the  outside  through  the  stomata. 
Usually  the  transpiration  takes  place  readily,  but  if  the 
outside  air  is  not  in  condition  to  take  up  moisture,  the 
cells  become  too  full  and  the  excess  is  passed  off  through 
organs  (the  hydathodes)  at  the  ends  of  the  vascular 
bundles.  The  drops  of  water  which  escape  from  the  ends 
of  the  hydathodes  are  called  guttation  drops.  Grass  blades 
and  strawberry  and  nasturtium  leaves  show  such  drops 
almost  every  morning  in  the  spring.  House  plants  like 
fuchsia  or  impatiens  will  produce  guttation  drops  if 
covered  for  a  few  hours  with  a  bell  jar.  Cool  a  portion 
of  the  jar  later,  noting  what  happens.  Give  an  expla- 
nation of  what  you  see. 


WORK   OF    THE  BEAN   LEAF  275 

LABORATORY    KXTKIIIMKN IS 

Hold  the  underside  of  a  geranium  Leaf  against  a  cool  window  pane  and 

note  the  moisture  which  is  condensed.     Try  other  leaves  in  tin-  .sun.-  way. 
With  clips  fasten  a  watch  crystal  to  a  growing  leaf  ami  seal  with  vaseline. 
Note  the  moisture  condensed.     Try  the  upper  side  of  the  saim-  lean 
Plunge   a   leaf   into   water   and   set   the    water   in    the   sun.     Do   small 
bubbles  appear  on  the  surface  of  the  leaf  ?     Where  ? 

Take  leaves  of  the  same  plant  and  coat  with  paraffin  one  leaf  on  both 
sides,  another  on  the  upper  side,  and  a  third  on  the  underside.  Lay  them 
aside  for  a  few  days.  Then  remove  the  paraffin  and  examine  all  the 
leaves.     Which  is  in  the  best  condition  ?     Why  ? 

Examine  with  a  microscope  the  epidermis  of  a  number  of  leaves  bom 
different  plants.  Note  the  irregular  epidermal  cells  and  the  stomata  cells. 
Are  the  stomata  arranged  regularly? 

Hold  a  leaf  up  to  the  light  and  notice  the  arrangement  of  the  veins 
and  soft  parts.  Study  a  cross  section  of  a  fresh  leaf  and  find  :  (1)  the  epi- 
dermal layer  on  top  ;  (2)  the  palisade  layer  below  it ;  (3)  the  wide,  spongy 
layer  ;  and  (4)  the  lower  epidermal  layer  with  stomata. 

Stand  the  petiole  of  a  leaf  in  red  ink  and  observe  how  the  color  spreads 
through  the  veins  of  the  leaf. 


•■o' 


210.  The  Work  of  the  Bean  Leaf.  — •  As  soon  as  the  bean 
plant  gets  its  plumule  into  the  air,  the  pale  leaves  unfold, 
turn  green,  and  increase  in  size.  The  stem  elongates, 
branches,  and  other  leaves  appear.  Bach  of  these  new 
leaves  is  held  out  from  the  stem  or  branch  in  a  position 
which  gives  the  leaf  the  greatest  possible  amount  of  air 
and  light.  The  leaves  of  the  plumule  begin  to  be  useful 
to  the  plant  as  soon  as  they  become  green.  Their  work 
is  most  important  in  the  life  processes  of  the  plant. 

Does  the  bean  plant  respire?  When  an  animal  respires, 
it  takes  oxygen  into  the  cells  of  its  body  ami  gives  off 
carbon  dioxide.  The  presence  of  this  gas  is  shown  by 
forcing:  the  air  that  comes  from  the  Lungs  through  a  tube 
into  limewater.     The  limewater  becomes  cloudy.     This  i> 

» 

a  simple  chemical  test  for  carbon  dioxide. 

If  a  growing  bean  plant  is  kept  tightly  covered  under  a 
glass  disk  for  twenty-four  hours  and  then  the  inclosed  air 


276  TYPICAL   FLOWERING  PLANTS 

is  forced  through  limewater,  the  clear  limewater  turns 
cloudy.  Thus  it  is  shown  that  the  bean  leaves  have  given 
off  carbon  dioxide.  The  only  life  process  which  is  known 
to  produce  carbon  dioxide  is  respiration.  Therefore  we 
can  say  that  the  plant  respires  and  that  this  life  process 
in  the  plant  is  similar  to  the  same  life  process  in  animals. 
See  pages  3  and  15. 

The  Manufacture  of  Food.  —  The  words  "manufacture  of 
food'  are  often  used  in  connection  with  plants.  This 
process  may  be  better  understood  by  comparing  it  with 
the  manufacture  of  some  article  in  a  factory.  To  manu- 
facture an  article,  there  must  be  a  building  with  rooms; 
machines,  and  power  to  run  them ;  and  various  substances, 
called  raw  materials,  which  are  to  enter  into  the  finished 
product.  In  addition  there  must  be  a  supply  of  water, 
pipes  in  which  to  carry  it,  and  forces  to  move  it.  Be- 
sides the  finished  product,  a  factory  always  yields  some 
waste  material.  When  the  product  has  been  finished,  it 
is  usually  packed  for  distribution  and  stored  in  a  room  to 
which  it  is  carried  on  tracks. 

In  the  leaf  factory,  the  cells  of  the  palisade  and  spongy 
layer  are  the  rooms.  The  machines  are  chlorophyll  bodies, 
and  the  power  is  furnished  by  the  sun.  The  raw  materials 
are  water,  containing  a  small  amount  of  mineral  matter 
obtained  from  the  soil,  and  carbon  dioxide  obtained  from 
the  air.  The  pipes  in  which  the  water  comes  are  the 
fibrovascular  bundles,  and  the  stomata  are  the  places 
where  the  air  enters. 

The  forces  which  move  the  raw  material  are  largely 
osmosis,  capillarity,  and  the  suction  caused  by  transpira- 
tion. The  materials  made  are  carbohydrates,  in  the  form 
of  starch  and  sugar,  and  protein.  Waste  material  is 
oxygen.  The  material  ready  for  carrying  is  usually  in 
the  form  of  sugar.     The  storehouse  may  be  the  stem,  the 


WORK   OF   THE  BEAN  LEAF 


277 


roots,  or  the  seeds  of  the  plant,  and  the  tracks  for  carry- 
ing the  food  to  the  storehouse  are  the  sieve  tubes  of  the 


Figure  268.  —  Germination  of  a  Monocotyledon. 


flbrovascular  bundles.  Part  of  the  carbon  dioxide  is  fur- 
nished by  the  plant's  own  respiration.  The  plant  takes 
from  the  carbon  dioxide  all  of  the  carbon,  but  only  a  part 
of  the   oxygen,   leaving 

some  of  it  to  be  thrown     r~\      ft])  "i1! 

off  as  waste. 

The  waste  oxygen 
thus  set  free  by  the  leaf 
in  the  manufacture  of 
food  can  now  be  used  by 
animals  in  respiration. 
Animals  are  constantly 
setting  free  carbon  di- 
oxide which  plants  must 
have  if  they  are  to  make 
food.  Animals  will  never 
be  able  to  use  up  all  of 
the  oxygen  in  the  air  so 


Figure  269. 


Rootlets  of  Two  Corn 
Plants. 


Showing  how  they  strive  for  food 
and  moisture. 


278 


TYPICAL   FLOWERING  PLANTS 


long   as  there  are  plenty   of   green   plants,  nor,  for  the 
same  reason,  will   there   ever  be  enough  carbon  dioxide 

to  poison  animals. 

Another  vital  process 
which  the  leaf  shows  is 
digestion.  It  is  difficult  to 
explain  how  the  food  is  di- 
gested in  plants,  but  scientists 
have  proved  satisfactorily 
that  digestion  does  take  place. 
After  the  food  is  digested, 
it  is  distributed  by  circula- 
tion. In  the  experiments  it 
was  shown  that  the  plant  has 
a  vascular  system,  and  that 
red  ink  was  carried  to  all 
parts  of  the  leaf.  Evidently, 
then,  a  plant  has  circulation. 
Food  to  be  used  by  the 
plant  cells  must  not  only  be 
prepared  by  digestion  and 
distributed  through  circula- 
tion, but  each  cell  must  take 
from  the  sap  what  it  lacks, 
and  build  this  food  into 
living  plant  protoplasm. 
This  process  is  called  as- 
similation and  as  a  result  of 
it  cells  grow,  divide,  and 
grow  to  full  size  again, 
thereby  increasing  the  size 
of  the  plant. 

Summary  of  the  work  of  the  bean  leaf :  (1)  It  performs 
respiration;   (2)  it  performs  transpiration ;   (3)  it  manu- 


Figure  270.  —  Corn  Plant. 
Showing  prop  roots. 


THE  CORN   SEED LlSd 


J7!» 


Figure  271.  —  Maple  Seedlings. 
Compare  with  Figure  274. 


factures  sugars  and  starches  (a  process  technically  known  as 

photosynthesis),  and  proteins;  (4;  it  digests  some  of  tin- 
food  that  it  has  made ;  (5)  it  assimilates  some  of  the  di- 
gested food  ;  (6)  by  cir- 
culation it  carries  some 
of  the  starch  and  protein 
to  other  parts  0f  the 
plant  and  brings  fresh 
raw  materials  into  the 
leaf;  (7)  it  gives  off 
waste  material  in  the 
form  of  oxygen. 

211.  The  Corn  Seedling-. 
—  When  the  corn  seed- 
ling begins  to  grow, 
its  tightly  rolled  leaves 
which  form  the  sharp  plumule  push  up  through  the  soil. 
Next  the  root  grows.  The  primary  root,  instead  of  re- 
maining the  largest,  as  in  the  case  of  the  bean,  sends  off  a 

number  of  branches 
about  the  same  size  a-> 
itself.  Like  those  of 
the  bean,  these  branches 
have  rootlets  and  root 
hairs.  There  is  little 
difference  between  the 
roots  of  corn  and  beans 
so  far  as  their  structure 
goes,  but  corn  roots  have 
neither      tubercles      imr 

nitrogen-gathering  bac- 
teria.     The   first    Leaves 

Figure  272.- M.crophotograph  of  of  (',,rn  :m'  likr  tl"'  lilt,'r 

Corn  Stem.  ones,  except    in  size,   be- 


hard  rind   " 

:     ifi  b 

ro-vascular 

bundles 

£ 

>» 

'■ ' 

<*rJ 

\  ■ 

J>  'U 

\  • 

\ 

'4 

280 


TYPICAL   FLOWERING   PLANTS 


cause  only  the  plumule  comes  above  the  ground.  The 
kernel  of  the  corn  remaining  in  the  ground  shrinks  as  the 
plant  grows  and  as  the  food  is  used.  The  modified  coty- 
ledon (scutellum)  dies  when  it  has  served  its  purpose  of 


Figure  273.  —  Stem  of  Corn. 
Showing  node  and  fibrovascular  bundles. 

transferring  to  the  young  seedling  the  food  stored  in  the 
endosperm. 

212.  The  Root  System  of  Corn.  —  There  are  many  fibrous 
roots  of  small  size,  which  extend  to  a  distance  of  several 
feet  in  every  direction.     Besides  these  underground  roots, 

the  corn  plant  has  aerial 
roots  growing  from  the 
lower  joints  of  the  stem, 
and  these  are  known  as 
prop  roots.  These  roots 
are  stout,  straight,  some- 
times green,  branching 
in  the  soil.  They  serve 
to  hold  the  plant  firmly 
in  the  soil. 

213.  The  Corn  Stem.  — 
While  the  roots  of  the 
bean  and  corn  are  similar 
in  structure,  there  are 
several  differences  in  the  stems  of  these  plants.  The  corn 
stem  has  no  central  region  filled  with  pith,  but  the  pith 
makes  up  the  greater  part  of  the  interior.  Scattered 
through    it    are    stringlike    parts,   fibrovascular   bundles, 


Figure  274. 


-Elm   and  Older    Maple 
Seedlings. 


THE   CORN   LEAF 


I'M 


Figure  275. — Seedlings. 

a,  Horse-chestnut  seedling  ;   b,  Honey 
locust. 


each  consisting"  of  xvlem 

and    phloem,    but    not 

arranged  in  any  regular 

order  (Figure  273).    Sur- 
rounding the   pith  is  a 

hard    rind    which  gives 

the  plant  stiffness.     The 

place  where  a  leaf  joins 

the  stem  is  called  a  node. 

Some    of    the    vascular 

bundles  of  the  stem  pass 

out   through   the   nodes 

and  as  veins  continue  on 

into    the    leaves.      The 

corn  stem  represents  the 

structure  of  all  monocotyledonous  plants,  as  the  bean  stem 

represents  all  of  the 
dicotyledons  which  live 
only  one  season. 

214.  The  Corn  Leaf.— 
The  leaf  of  the  corn 
has  no  petiole,  but  is 
attached  to  the  stem 
by  a  clasping  lias.-. 
This  base  protects  the 
•tenderest  part  of  the 
stalk,  which  is  just 
above  the  node.  At 
the     point     where     the 

clasping  pari   and   the 

blade  of  the  leaf  meet, 

there  is  a  collar  which 
prevents    water    from 

running    down     inside 


Figure  276.  —  Older  Horse-chestnut 
Seedlings. 

Note  the  palmately  compound  leaves. 


282 


TYPICAL   FLOWERING   PLANTS 


the  clasping  base.     The  corn  leaf  is  long  and  narrow  ;   it 
curves,  and  has  wavy  edges.     Veins  run  from  the  base 

to  the  tip  without  branch- 
ing, giving  the  parallel 
venation  characteristic 
of  the  monocotyledons. 

A  cross  section  of  a 
corn  leaf  shows  that  it 
has  the  same  structure 
as  the  bean  leaf.  The 
stomata  are  aided  in  pre- 
venting undue  transpira- 
tion during  dry,  hot 
weather  by  the  tight 
rolling  of  the  leaf. 

215.  Other  Seedlings. 
—  All  dicotyledonous 
plants  are  like  the  bean 
in  having  two  cotyledons,  but  differ  in  other  respects. 
Peas,  for  instance,  do  not  bring  their  cotyledons  above 
ground.  Morning  glories  have  their  cotyledons  folded  in 
the  middle  ;  maple  seed- 
lings have  theirs  folded 
on  each  other.  Many 
seedlings  have  leaves 
which  differ  in  shape 
from  those  of  the  mature 
plant  (Figure  271). 

All  monocotyledonous 
plants  are  alike  in  hav- 
ing only  one  cotyledon 
which  usually  remains  in 

the  soil  during  germina-  Figure  278.  —  Roots  of  Radish. 

tion.        The    first     seed-  Containing  stored-up  food. 


Figure  277. — Wheat  Seedlings. 

a,  grown  in  sunlight ;  b,  grown  in 
the  dark. 


OTHER   BOOTS 


283 


ling  leaves  look  more 
like  the  later  ones  than 
in  the  dicotyledons. 

216.  Other  Roots.  — All 
roots  serve  to  hold  the 
plant  in  place  and  to 
collect  water.  Some 
roots  have  other  uses  in 
addition.  The  roots  of 
beets,  turnips,  carrots, 
parsnips,  and  radishes 
store   up   food   the   first 


Figure  279. 
A  valuable  food. 


-  Roots  of  Beet. 
See  also  Figure  296. 


year  of  their  growth.  If,  however,  they  are  planted  a 
second  year,  they  use  the  stored-up  food  to  produce  fruit 
and  seeds  (Figures  278  and  279). 

Ivy  has  two  kinds  of  roots,  one  in  the  ground,  the  other 


Figure  280.  —  Alfalfa  Root. 
Compare  with  Figures  269,  281.  and  283. 


284 


TYPICAL  FLOWERING  PLANTS 


along  the  sides  of  the  stem  to  help  the  plant  cling  to  its 
support.  Roots  which  grow  in  the  air  are  called  aerial 
(Latin,  aer,  air)  roots  (Figure  281). 

Sometimes  roots  arise  from  the  bottom  of  a  stem  which 
has  been  cut  or  broken  from  the  main  plant,  as  in  the  case 
of   a  geranium  slip.     Such  roots  are  called  adventitious. 

The  willow  is  a  tree  which  is 
easily  grown  from  a  twig,  be- 
cause it  readily  forms  adventi- 
tious roots. 

Most  roots  grow  downward 
in  soil  which  is  well  cultivated. 
The  stimulus  which  causes  them 
to  take  this  direction  is  gravity, 
or  as  scientists  say,  they  are  show- 
ing geotropism  (ge-6t'r5-pizm  : 
Greek,  ge,  earth  ;  tropos,  a  turn) . 
Other  influences  governing 
the  direction  in  which  roots 
grow  are  the  presence  of  water 
and  obstacles.  When  a  root 
turns  in  the  direction  which  will  give  it  the  best  supply 
of  water,  it  is  exhibiting  hydrotropism  (hi-drot'ro-pizm : 
Greek,  hydro,  water;  tropos,  a  turn).  When  a  root 
turns  aside  to  avoid  an  obstacle  it  acts  in  response  to 
the  stimulus  of  touch  or  contact,  showing  thigmotropism 
(thig-mot'ro-pizm:  Greek,  thigmos,  touch  ;  tropos,  a  turn). 
The  roots  of  poplar,  willow,  and  soft  maple  trees,  in  seek- 
ing water,  often  clog  sewer  pipes  by  filling  them  with 
rootlets  after  they  have  gained  an  entrance  through  a 
joint,  a  habit  which  renders  them  objectionable  as  shade 
trees. 

In  agriculture,  the  soil  is  made  fine  and  porous  to  help 
the  roots  of  plants  get  food  and  moisture. 


Figure  281.  —  Aerial  Roots 
of  Ivy. 


OTHER  STEMS 


ln:> 


LABORATORY   WORK    ON    ROOT8 

Test  the  roots  of  beet,  carrot,  parsnip,  radish,  and  turnip  with  iodine 
for  starch  ;  with  Fehling's  solution  for  sugar;  with  nitric  acid  for  protein. 
Examine  a  large  number  of  roots  and  report. 


Dandelion 
Plantain 
Carrot    . 
Dahlia   . 
Corn 
Ivy    .     . 


Roots  All 
Ondbr- 

GBOTJND 


Roots  not 
A  i.i.  Dndeb- 

GBOCND 


l'l'.IMARV 

Kooi  - 


FlBBOl  - 

Booi  - 


I  A  I. 

BOOTB 


217.  Other  Stems. — The  stems  of  all  plants  are  like  the 
stem  of  the  bean  in  the  work  which  they  do,  but  some 
stems  have  additional  uses.  The  stems  of  such  plants  as 
Solomon's  seal,  dogtooth  violet,  and  Jack-in-the-Pulpit 
store  up  surplus  food.     These  stems  are  thick  and  fleshy, 

and  remain  underground  from 
year  to  year.  For  this  reason 
they  are  often  mistaken  for 
roots,  but  they  can  always   be 


Figure  282.  —  Potato. 
The  eyes  are  buds. 


Figure  283.  —  Dahlia  "Roots." 
An  underground  stem  which  stores  food. 


286 


TYPICAL   FLOWERING  PLANTS 


^^^^. 

^x^^H 

[  V  ip 

«  1 

1  \  ^ 

■«►     «#       fl 

Figure  284.  —  Microphotograph  of 
Sunflower  Stem. 


recognized  as  stems  by  the  buds  of  new  leaves,  or  the  scars 
of   former  leaves.     Underground  stems,   called  rhizomes 

(ri'zom)  or  rootstocks, 
send  up  aerial  stems 
which  live  through  one 
season. 

Stems  like  the  water 
lily,  which  grow  in 
water,  have  large  air 
spaces  to  carry  air  to 
the  roots  that  lie  in  the 
mud  at  the  bottom  of 
the  water. 

The  trunks  of  trees 
are  stems.  In  evergreen 
trees  (pine,  spruce,  etc.) 
the  trunk  puts  out 
branches,  but  does  not  divide,  and  tapers  from  base  to  tip. 
Such  trunks  are  called  exeurrent  (Latin,  ex,  out ;  curro,  to 
run).  In  the  case  of  the 
elm  tree  and  many  others, 
the  trunk  itself  divides 
again  and  again.  Such 
a  trunk  is  called  deliques- 
cent (Latin,  de,  from  ; 
liquescere,  to  become  liq- 
uid). 

An  interesting  com- 
parison is  that  between 
the  climbing  and  twining 
stems  of  plants,  especially 
vines,  and  the  sturdy 
trunks  of  trees.  The 
morning  glory  is  a  plant  Figure  285.  — Cleft  Grafting. 


OTHER   STEMS 


2S7 


Figure  286.  —  Whip  Grafting. 


which  twines  around  some  support  and  thus  is  able  to  gel 
sunlight  for  its  many  leaves.  Twining  plants  of  the  same 
kind  always  curve  in  the   same   direction.      In   twining 

around  any  object  they 

touch,    climbing    plants 

are  responding  to  thig- 

motropism. 

The  wild  grapevine  is 

a  plant  which  climbs  to 

the     top    of     trees     by 

means   of   a   long,   leaf- 
less stem.     Such  plants, 

common   in    the    forests 

of  tropical  countries,  are 

called  lianas. 

Woody  stems  have  a 

structure  which   differs 

from  that  of  the  soft  bean  stem.      On  the  outside  is  the 

brown  bark  in  which  are  lenticeh,  holes  which  allow  air  t<> 

enter.      Under  this   is  a  layer   of  green   bark,  the  out» *r 

edge  of  the  phloem  of  the  vascular  bundles.     Between  the 

phloem  and  the  xvlein  of 
each  vascular  bundle  is  a 
region  of  rapidly  dividing 
cells,  which  is  called  the 
CCDnhilUH,  When  the  \  as- 
cular  bundles  are  crowded 
close  together  the  cam- 
bium of  adjoining  bundles 
touches,  thus    forming  a 

ring  around  the  tree  (Figure  284).     The  outer  edge  of  this 

cambium   layer   is   always    turning    to    phloem,    and    the 

inner  to  xyleni. 

A  woody  twig  like  the  horse-chestnut  (Figure  290)  has 


Figure  287.- — Budding. 


288 


TYPICAL  FLOWERING  PLANTS 


:^=~ 


Figure  288. — -Twining 
Stem  of  Dodder. 


Figure  289.  —  Creeping  Stem  of 
Trailing  Arbutus. 


a  bud  at  the  end  called  a  terminal  bud,  and  along  the  branch 
are  other  buds,  named  lateral  buds.  These  buds  are 
covered  with  scales  and  contain  the  leaves  of  the  next 
season  arranged  in  a  definite  manner.     Sometimes  buds 


Figure  290.  —  Horse-chestnut. 


OTHER   STEMS 


289 


Figure  291.  —  Types  of  Twigs. 

a,  maple;  b,  elm;  c,  walnut;  d,  catalpa 
e,  ash  ;  /,  linden. 


contain  both  leaves  and 
flowers.  As  a  bud 
opens,  the  scales  drop 
off  leaving  on  the  twig 
scars  crowded  together 
in  indistinct  rings.  The 
growth  of  a  twig  in  the 
preceding  year  can  be 
seen  by  noting  the  dis- 
tance between  the  tip  of 
the  twig  and  the  first 
group  of  indistinct  rings, 
which  marks  the  posi- 
tion of  the  terminal  bud  of  last  year.  A  study  of  the 
buds  on  a  branch  shows  where  the  new  branches  will  form. 
The  place  where  the  leaves  of  last  year  were  attached 
shows  on  the  bark  as  scars,  called  leaf  scars.  In  each  leaf 
scar  are  a  number  of  small  dots.     These  dots  are  the  ends 

of  the  vascular  bundles 
which  grew  from  the 
stem  into  the  leaf. 

A  cross  section  of  a 
woody  stem  shows  a 
central  pith  surrounded 
by   one   or   more    rings 


Figure  292.  —  Cherry  Twigs. 
Leaf  buds  and  fruit  buds. 


Figure  293.  —  Sections  of 
Woody  Stem. 


of  wood.     The  pith  and  the  bark  are  connected  by  narrow 
lines    of    pith   called   medullary   rays   (Figure   i?(.*3).      A 


290 


TYPICAL   FLOWERING   PLANTS 


4  V  4ij=p  >J.;»Jf 


woody  layer  examined  under  a  microscope 
shows  large  cells  on  the  inner  side  of  each 
layer,  and  smaller,  thick-walled  cells  on  the 
outer  side.  The  large  cells  are  formed 
when  conditions  are  favorable  to  rapid 
growth,  and  the  smaller  cells  when  condi- 
tions  are  less  favorable  (Figure  294).  A 
dry  season  may  check  growth  during  the 
middle  of  the  summer  so  that  an  indistinct 
rinsr  will  occur  between  two  distinct  ones. 
This  makes  it  impossible  to  tell  accurately 
the  age  of  a  tree  by  counting  the  rings. 

Every  part  of  the  woody  stem  has  a 
distinct  use.  The  bark  protects  the  tender 
growing  parts  within.  The  xylem  carries 
water  containing  food  materials  from  the 
roots  to  the  leaves,  and  the  phloem  carries 
to  other  parts  of  the  plant  for  use  or  for 
storage  the  food  which  has  been  made  from 
the  raw  materials.  As  the  stem  increases 
in  thickness,  only  the  outermost  layers  of 
xylem  continue  to  carry  water,  for  the  inner 
layers  fill  up  with  a  sub- 


stance which  hardens 
into  wood.  Although 
they  are  dead,  these 
layers  are  still  of  use  in 
giving  stiffness  to  the 
tree.  The  work  of  the 
tree  goes  on  without 
them,  as  is  shown  when 
a  tree  decays  in  the  cen- 
ter. The  pith  in  the 
center  of  a  tree  and  in 


Figure  294. — 
Wood  of  Spruce. 

Greatly  magni- 
fied. 


WiL 


Figure  295. 


Photograph  of  Sections 
of  Wood. 


OTHER   STEMS 


L>(.)1 


the  medullary  rays  serves  as  a  storehouse    for   food  and 
as  lateral  conductors  of  sap. 

Liquids  are  always  passing  along  the  paths  indicated, 
but  this  process  is  observed  most  readily  in  the  spring 
when  the  sap  runs  from 
the  broken  end  of  a 
branch.  When  the 
leaves  are  grown,  much 
of  the  water  carried  to 
them  is  lost  by  transpira- 
tion, and  little  is  left  to 
be  carried  back.  In  the 
spring,  water  is  carried 
down,  as  well  as  up. 

Most  of  our  common 
lumber  is  made  by  saw- 
ing the  trunks  of  trees 
lengthwise.  Sawing  in 
this  way  shows  the 
annual  rings  as  long  lines  (Figure  295),  but  does  not  show 
the  medullary  rays  except  in  a  few  boards.  Lumber  t<>  be 
used  in  furniture  is  often  cut  so  as  to  show  as  many  med- 
ullary rays  as  possible.  The  rays  are  lighter  in  color  and 
more  glistening  than  the  woody  layers. 

A  tree  grows  by  adding  a  layer  of  new  wood  each  year. 
The  branches  of  the  current  season  have  only  a  single  ring 
of  wood,  while  those  of  the  season  bet  ore  have  two  rings, 
and  so  on. 

LABORATORY   STUDY   OF   TWIGS 

Examine  a  twig  from  a  horse-chestnul  tree,  and  identify    1 1  the  termi- 
nal   buds;    (2)   lateral    buds;    (8)   leaf   scars ;    (4)   dots    in    leaf 
(5)  rings;  ((>)  scales  covering  buds;   (7)  breathing  pores  or   lentta 
Dissect  a  bud  to  see  what  it  contains.     Make  a  cross  Bection  of  a  stem 

and  find  (1)  the  pith  ;   (2)   woody  rings;    (3)   bark  in  two  layers. 


Figure  296. —  Food  Storage. 
Creeping  stem  of  Canada  ginger. 


292 


TYPICAL  FLOWERING  PLANTS 


Figure  297.  —  Celery  Plant. 
Compare  with  Figures  279  and  282. 


Figure  299.  —  Twining  Petiole 
of  Clematis. 


Figure  298. —  Cabbage  Plant. 


Figure  300.  —  Twining  Petiole 
of  Nasturtium. 


OTHER   LEAVES 


293 


Examine,  with  a  microscope,  a  section  of  wood,  looking  for  the  pith, 
medullary  rays,  and  annual  rings.  Examine  the  boards  in  the  room  and 
furniture  to  find  the  annual  rings  and  medullary  rays. 

REPORT   OX   TWIGS 
Record  your  observations  in  a  report. 


00 

a 
- 

*-* 

O0 

- 

00 

Q 
D 

pq 

< 
K 

M 

i. 

- 
- 
- 

— 

H 

_ 
SB 

- 
O 

- 

i 

oo 

- 
-< 

— 

■ 

- 
- 
- 

- 
_ 
•< 

O 

W 

CO 

o 

£ 

- 

- 

. 

O 

■A 

© 

O 

H 

z 

w 
7. 
W 
- 
Y. 
< 

< 

c 

ao 

r" 

H 
H 
Z 
O 

O 

—   0 

H 
0 
r. 
< 
H 
■i. 

P 

i. 

M 
w 

7. 

- 

00 

- 
H 

h3 

: 
z 

- 

- 

- 

-J 

i 
- 
M 

> 

/ 
_ 
- 
6 

H 

Z 

- 

►3 

— 
- 

:- 
7 

/ 

- 
- 

- 

Geranium  . 

Horse- 

chestnut  . 

Lilac      .     . 

Maple     .     . 

218.    Other  Leaves.  —  All  leaves  have  the  same  work  to 
do  as  the  leaves  of  the  bean,  but  some  leaves  have  other 


Figure  301.  —  Barberry  Leaves. 
Showing  how  a  leaf  may  become  a  thorn. 

work  in  addition.      The  storage  of   food  is  one  additional 
task.      Celery  and   rhubarb  (pieplant)  store  food  in   the 


294 


TYPICAL   FLOWERING  PLANTS 


thick,  fleshy  stalks  of  their  leaves.  In 
cabbages,  the  blade  of  the  leaf  is  the 
place  of  storage,  while  in  onions  it  is 
the  thick  enlarged  base  of  the  leaves. 

Clematis  and  nasturtiums  climb  by 
twining  the  petioles  of  their  leaves 
around  a  support. 

Pitcher  plants  have  leaves  which  hold 
water  and  entrap  insects.  Venus's  fly- 
trap and  sundew  both  use  their  leaves  to 
catch  insects. 

Plants  which  have  leaves  lasting  more 
than  one  year  are  called  evergreen;  and 
those  that  shed  their  leaves  every  autumn 
are  called  deciduous  (Latin,  deciduus, 
falling  off).  The  blade  of  some  leaves 
is  in  one  piece,  as  is  the  case  with  the 
geranium.  Such  leaves  are  called  simple 
leaves  to  distinguish  them  from  the  com- 
pound leaves,  like  the  rose  or  horse-chestnut,  in  which  one 
petiole  supports  several  leaflets. 


j****'^ 

M 

I 

($" 

■ 

Figure  302.  —  Pea 
Plant. 

Leaves  modified  in- 
to tendrils. 


Figure  303.  —  Leaf  of  Oak. 
Simple  leaf. 


Figure  304.  —  Leaf 

of  Elm. 

Simple  deciduous 

leaf. 


LABORATORY   STUDY 


295 


LABORATORY    EXPERIMENT    TO    PROVE    THAT    LEAVES 

GIVE   OFF    WATER 

Wrap  in  waxed  paper  a  jar  containing  a  small  plain,  and  cover  the 
earth  with  half  an   inch   of  melted  paraffine   to  prevent  evaporation. 

Weigh  the  plant  each  day  and  note  the  amount  of  water  l<»st  by  transpir- 
ation through  the  stomata. 


LABORATORY  STUDY  OF  LEAVES 

Examine  as  many  leaves  as  possible  and  record  the  facts  which  yon 
have  learned  about  them  in  a  report  like  the  following  : 


Leaves 
Simple 

Lb  A  VK8 

Compound 

]  )  K<   1 1 1 1   •  ■  1   - 

Stoeaoi 

<   LIMBING 

Cherry     . 

Maple 

Lilac   .     . 

Ash     .     . 

Rose    . 

Horse- 

chestnut 

. 

Etc.     . 

219.    Comparison  of  a  Monocotyledonous  with  a  Dicotyledonous 

Plant.  — 

Monocotyledon 

Dl<  OTV  LEDOM 

Corn 

r.KAN 

Epidermis. 

Same  structure. 

Cortex. 

Root. 

Endoderm. 
Central  cylinder. 
Root  caps. 
.Root  hairs. 

Hard  outside. 

Thin  epidermis  in  young  plants. 

bark  in  <>M. 

Much  pith. 

Pith  confined  to  center  and  med- 
ullary rays. 

Stem. 

Scattered       vascular 
bundles,    no    cam- 

Vascular    bundles    form    rinp, 

phloem   out.   xylctn  in.  cam- 

bium. 

bium  between. 

Vascular         bundles 

Vascular      bundles      pass     to 

uiven      off       from 

branches  and  to  leave  3. 

1     nodes, 

to  leaves 

• 

296 


TYPICAL  FLOWERING  PLANTS 


Monocotyledon 
Corn 
'  Long,  simple,  and  nar- 
row. 
Leaves.  <  No  petiole,  but  clasp- 
ing base. 
Parallel  veins. 


Dicotyledon 
Bean 

Broad,  compound. 
Petiole. 
Netted  veins. 


220.  The  Bean  Flower.  —  Just  before  the  bean  plant  reaches 
full  size,  greenish  buds  appear  in  clusters  on  the  ends  of 
the  branches.  These  green  buds  grow  into  the  bean 
flower.  This  flower  is  made  up  of  a  number  of  parts,  all 
of  which  have  an  important  work  to  do  in  producing  the 
bean  seed. 

The  parts  of  the  bean  flower  have  technical  names  which 
it  is  necessary  to  learn  in  order  thoroughly  to  understand 

flowers.  The  green, 
outermost  part,  called 
the  calyx  (Greek,  kalyx, 
cover),  is  made  up  of 
separate  sepals  (Latin, 
separ,  separate)  which 
form  a  cup  in  which  the 
rest  of  the  flower  is 
fastened.  The  calyx 
protects  the  delicate 
parts  of  a  flower  while 
they  are  small.  Within 
the  calyx  is  the  white 
and  much  larger  part 
called  the  corolla-  (Latin,  corolla,  crown).  The  corolla 
(Figures  305  and  307)  is  made  up  of  irregular  shaped  struc- 
tures called  petals  (Greek,  petalon,  leaf) ;  within  the  corolla 
there  is  a  group  of  stamens  (Latin,  sto,  stand)  which  are 
recognized  easily  by  their  slender  stalks,  filaments,  and 
enlarged  tips  or  anthers.     At  the  exact  center  of  the  bean 


Figure  305.  —  Diagram  of  Bean  Flower. 


THE  BEAN   FLOWER 


297 


flower  and  within  the  group  of  stamens  is  the  pistil.  Tin- 
stamens  and  pistil  are  the  important  parts  <»l'  the  bean  flower 
because  they  produce  the  bean  seed  (Figures  306  and  307). 
The  stamen  bears  in  the  enlarged  tip  many  minute  bodies 

which  are  known  as  pollen  or  pollen  grains 
(Latin,  pollen,  fine  flour).  The  pistil  is 
divided  into  three  parts:  (1)  a  slightly  ex- 
panded and  sticky  tip,  the  stigma  (Greek, 
stigma,  point);  (2)  a  slender  portion  con- 
necting the  stigma  with  the  much  larger  base, 
the  style  (Greek,  stylos,  pillar) ;  (3)  and  the  swol- 
len base,  the  ovary  (Latin,  ovum,  egg~).  See 
Figure  306.  The  ovary  contains  small,  rounded 
bodies  called  ovules  which  ripen  into  seeds. 

The  bean  flower  is  a  complete  flower,  be- 
cause it  has  all  of  these  parts:  calyx,  corolla, 
stamens,  and  pistil.  It  is  also  said  to  be 
perfect  because  it  contains  in  the  same  flower 
the  two  organs  needed  to  produce  seeds,  the 
pistil  and  stamens. 

The  word  pollination  is  used  to  describe  the 
carrying  of  the  pollen  from  the  anther  of  the 
stamen  to  the  stigma  of  the  pistil.  This  may 
be  done  by  the  wind,  by  insects,  or  by  the 
contact  of  a  stamen  with  a  stigma.  The  bean 
flower  secretes  a  sweet  fluid,  nectar,  at  its  base, 
which  is  the  fluid  the  bees  gather  to  make  in t « » 
honey.  When  a  bee  alights  on  a  bean  flower,  it  pushes 
its  head  among  the  inner  parts  to  get  the  nectar.  In 
withdrawing  its  head,  pollen  is  brushed  off  and  the  hairy 
body  of  the  bee,  especially  the  head,  is  covered  with  it. 
When  the  bee  puts  its  head  into  the  nexi  bean  flower, 
some  of  this  pollen  is  caught  by  the  sticky  stigma  past 
which  the  bee  has  to  push  to  get  the  nectar.      Thus  the 


Figure  306. 
—  Diagram 
of  Stamen 
(above)  and 
Pistil  (be- 
low). 


298 


TYPICAL   FLOWERING   PLANTS 


stigma  is  covered  01 
pollinated  with  pollen 
from  the  stamens  of 
another  flower,  and  the 
first  step  is  taken  which 
results  in  the  formation 
of  a  bean. 

221.  The  Corn  Flower. 
—  The  flower  of  the 
corn  is  imperfect,  for  it 
lacks  one  of  the  two 
parts  necessary  to  make 
a  seed.  Both  parts,  however,  are  found  on  the  same  plant, 
the  stamens  in  the  "  tassel "  (Figure  270)  at  the  top  of  the 
stalk,  and  the  pistils  on  the  "  ear  "  (Figure  310)  at  the  side 


Figure  307.  —  Sweet  Pea  Flower. 


Figure  308.  —  Fly  Pollinating  Wild  Carrot. 


FERTILIZATION 


2\)W 


Figure  309.  —  Swallow-tail  Butterfly 
Pollinating  Persian  Lilacs. 


of  the  stalk.     The  style  of  each  pistil  protrudes  from  the 

ear  of  corn  as  a  long  green  thread,  called  the  silk.      The 

pollen  is  light  and  abun- 
dant, and  falls  from  the 

stamen  with  every  stir 

caused    by    the    wind. 

The  stigma  at  the  end 

of  the   style   is  sticky, 

as  in  the   bean.     In  a 

field     of     corn     where 

many  plants  are  shed- 
ding pollen  at  the  same 

time,  it  is  almost  certain 

that    every    pistil    will 

receive     at     least    one 

grain  of  pollen.     It  is  to  secure  thorough  pollination  that 

corn  is  planted  in  fields,  with  the  plants  close  together. 

Plants  which  have  both  sta- 
mens and  pistils  on  them,  but 
on  different  flowers,  are  called 
monoecious  (mo'ne'shfis  :  Greek, 
monos,  one  ;  oikus,  house).  Plants 
which  have  only  staminate  or 
only  pistillate  flowers  are  calif  1 
dioecious  (di-e'shus:  *//.  twoj 
oikus). 

222.  Fertilization. — The  second 
step  in  the  production  of  a  ^'kh\ 
is  fertilization.  By  this  we  mean 
the  union  of  the  sperm  DUCleUfi 
of  the  pollen  cell    (  male  parent  ) 

with  that  of  the  egg  cell  in  the  ovule  (female  parent  ). 
The  pollen  grain  has  two  coats,  an   outer  ami   an   inner. 

The  outer  is  thicker  than  the  inner,  but    it  has   thin  spots 


Figure  310.  —  Corn  Flower 
with  Pistils. 


300 


TYPICAL   FLOWERING   PLANTS 


in  it.  When  a  pollen  grain  falls  on  a  sticky  stigma,  the 
inner  coat  pushes  out  through  one  of  the  thin  places, 
forming  a  tube  into  which  all  the  contents  of  the  pollen 
grain  flow.  The  contents,  at  this  time,  consist  of  two 
nuclei  and  a  small  amount  of  protoplasm.  The  pollen 
tube  grows  and  pushes  its  way  through  the  loose  tissue 
of  the  stigma  till  it  reaches  the  ovary  containing  the 
ovules  (Figure  311,  a,  6). 

The  ovules  are  attached  to  the 
sides  of  the  ovary.     Each  has  a 


Figure  311.  —  a,  pollen  grains  growing 
through  pistil ;  b,  same  magnified ; 
c,  nuclei  of  pollen  and  egg. 


thick  coat  called  the  integument  which  does  not  quite  meet 
at  one  spot,  known  as  the  micropyle.  Inside  the  ovule  is 
the  embryo  sac  containing  the  egg  cell  and  a  few  other  cells. 

When  the  pollen  tube  reaches  the  micropyle  of  an 
ovule  it  enters,  touches  the  egg  cell,  and  bursts.  The 
male  nucleus  unites  with  the  nucleus  of  the  egg,  and  fer- 
tilization is  accomplished  (Figure  311,  c).  The  other  nu- 
cleus of  the  pollen  tube  usually  unites  with  a  nucleus 
near  the  center  of  the  embryo  sac  and  helps  to  form  tissue 
which  may  be  of  use  to  the  growing  embryo  or  may  form 
a  part  of  the  mature  seed. 

The  fertilized  egg  cell  soon  begins  to  divide  and  grow,  and 


OTHER   FLOWERS 


:-;i )  l 


finally  it  develops  into 
the  embryo,  consisting 
of  plumule,  hvpocotyl, 
root,  and  cotyledons. 
The  integument  changes 
to  testa,  food  is  stored  up 
for  the  embryo,  and  the 
seed  is  ripe,  ready  to  start 
a  new  ijlant,  although  it 
may  have  to  wait  for 
vears  before  conditions 
allow  it  to  sprout. 

223.  Other  Flowers.— 
Flowers  like  the  bean 
which  have  all  the  parts  usually  found  in  a  flower  —  sepals, 


Figure  312.  —  Pistillate  and  Stami- 
nate  Flowers  of  Willow. 


0& 


Figure  313. — Violet. 
a,  cleistogamous  flowers. 


302 


TYPICAL   FLOWERING  PLANTS 


petals,  stamens,  and  pistil  —  are  complete.  As  we  have  seen, 
they  are  also  perfect  because  they  have  in  the  same  flower 
stamens  and  pistil,  the  parts  necessary  for  the  production 
of  seed.  An  imperfect  flower  may  be  staminate,  having 
only  stamens,  like  the  tassel  of  the  corn,  or  pistillate,  hav- 
ing only  pistils,  like  the  ear  of  the  corn  (Figure  312). 
So  an  incomplete  flower  may  lack  either  sepals  or,  as  is 
more  common,  petals.  Hepatica  is  an  example  of  a  flower 
which  lias  no  petals,  but  its  sepals  are  colored. 

Regular  flowers  are  those  in  which  all  the  parts  of  the 
same  kind  are  the  same  size  and  shape,  as  in  the  blossom 
of  the  apple.  In  irregular  flowers  all  the  petals  or  sepals 
are  not  of  the  same  shape.  The  bean  is  an  irregular 
flower,  and  so  is  the  violet. 

Cleistogamous  flowers  (klis-tog'a-mus :  Greek,  klistos, 
closed  ;  gamos,  marriage)  are  found  in  the  violet  (Figure 
313)  and  pansy  in  addition  to  the  flowers  of  the  ordinary 
type.  These  are  formed  underground  near  the  surface, 
have  no  colored  parts,  usually  only  one  stamen,  and  they 
never  open.     They  produce  many  seeds,  however. 

FIELD   AND   LABORATORY   STUDY 

Study  flowers  in  field  and  laboratory,  and  record  the  results,  using  the 
following  table  as  guide. 


Geranium  . 
Castor  bean 
Salvia  .     . 
Nasturtium 
Pansy  . 
Etc.       .     . 


O  1= 
o  K 

—  — 

-  - 

Corolla 
Lacking 

Stamens  only 
in  a  Flower 

Pistils  only 
IN  a  Flower 

X 

X 
X 

c  ~ 
■J  w 


Carolus  Linnaeus  (ihe  Latinized  form  of  the  name  Karl  von 
Linne)  was  born  in  1707  and  died  in  1778.  He  was  a  celebrated 
Swedish  botanist  and  naturalist. 

Linnaeus  went  to  the  University  of  Upsala  in  1728,  attracted 
by  the  fame  of  Rudbeck,  the  Professor  of  Botany,  whose  assistant 
he  became. 

In  1732  he  explored  Lapland.  Later,  while  studying  in  Holland, 
he  wrote  works  on  botany  which  attracted  wide  attention.  In 
1741  he  became  Professor  of  Botany  at  Upsala,  whither  his  fame 
attracted  students  from  many  foreign  countries.  Linnaeus'  sys- 
tem of  plant  classification  greatly  promoted  the  study  of  botany 
in  his  day. 


OTHER   FLOWERS 


303 


Figure  314.  —  Two-parted  Flower 
of  Mint. 

Note  the  convenient  place  for  the  bee 
to  alight ;  b,  stamens  in  usual  position  ; 
c,  stamens  bent  down  by  bees.  Pollen 
will  be  shaken  on  to  the  bee  and  carried  to 
another  flower. 


The    classification    of 

plants   by   stamens  and 

pistils  was  originated  by 

Linnaeus,  the  usual  name 

given  to  Carl  von  Linne 

(1707-1778),  the  Swed- 
ish    botanist.       During 

the  period  of  his  studies 

many  new  plants   were 

beinsr    brought    to    the 

attention    of     botanists 

by  the  traders  who  were 

constantly     penetrating 

to    parts    of   the    world 

hitherto     but      little 

known.     In    1737    Lin- 

nams       published       his 

famous  book,  G-enera  Plantarunu  in  which  he  gave  special 

names    in    the    nomenclature    of    plants,    and    also     first 

enunciated  the  principles  of  defining  general  species  and 

the  use  of  specific  names. 
For  his  achievements 
in  the  field  of  botany 
Linnaeus  was  elevated 
to  the  nobility. 

Flowers  are  also  classi- 
fied according  to  their 
method  of  pollination, 
that  is,  whether  by  in- 
sects or  by  the  wind. 
Insects  have  an  objecl  in 
visiting    flowers,   for  in 

Figure  315.  — Lady  Slipper.  them       they       find       the 

Pollinated  by  insects.  nectar  which  tliey  make 


304 


TYPICAL  FLOWERING  PLANTS 


into  honey,  or  they  find  pollen,  which  they  eat  and  feed 
to  their  young.  Insects  are  attracted  to  flowers  by  their 
strong  odor  or  bright  colors,  or  by  both. 

One  of  the  most  interesting  studies  in  biology  is  the 
relation  which  exists  between  certain  flowers  and  the 
insects  which  pollinate   them.     In   the   case  of  salvia  or 

flowering  sage,  for  example,  the  ir- 
regular corolla  offers  the  bee  a  con- 
venient place  to  alight.  To  suck  up 
the  nectar  the  bee  must  push  its  head 
into  the  cup  of  the  flower  where  it  is 
forced  to  brush  against  the  stigma 
which  becomes  covered  with  the  pollen 
from  the  last  salvia  flower  which  the 
bee  visited.  When  the  bee  withdraws 
its  head  it  becomes  dusted  with  pollen 
from  the  anthers  which  bend  down 
and  touch  the  back  of  the  insect. 
The  stamens  and  pistil  of  salvia  do 
not  mature  at  the  same  time  (Figure 
317),  so  that  the  bee  can  carry  pollen 
only  from  flowers  in  which  the  stamens 
are  ripe ;  and  the  pistil  will  receive 
pollen  only  in  the  flowers  that  have  a 
ripe  pistil. 

Certain  orchids  have  deep  tubes 
from  which  the  nectar  can  be  drawn 
only  by  insects  like  large  moths  which  have  long  sucking 
organs.  Many  orchids  have  their  pollen  in  masses. 
These  masses  stick  to  the  head  of  the  insect  visitor, 
and  hang  down  while  it  is  passing  to  another  flower. 
In  this  position  the  mass  is  almost  certain  to  be  rubbed 
off  on  the  stigma  of  the  second  flower.  Red  clover 
is  dependent   on   bumble   bees   for  pollination,  for  they 


Figure  316.  —  Flower 
of  Columbine. 

Showing  spurred 
petals.  Only  a  long- 
tongued  insect  can 
reach  the  nectar.  Note 
the  bunch  of  stamens 
upon  which  the  insect 
alights. 


POLLINATION 


:m 


have  a  tongue  of  the  length  to  get  the  nectar.     The  pollen 
is  carried  as  in  the  case  of  the  bean. 

Flowers  which  are  pollinated  by  wind  have  no  need  of 
color  or  of  odor,  but  they  have  pollen  which  is  Light, 
abundant  (for  much  of  it  is  lost),  and  easily  shed  from 
the  anthers.  The  stigma  is  feathery,  thus  offering  more 
surface  for  the  grains  of  pollen.  Grass  and  corn,  as  we 
have  seen,  are  examples  of  flowers  pollinated  by  the  wind. 
It  is  an  advantage  in  securing  proper  pollination  for  such 
plants  to  grow  close  together. 


LABORATORY   STUDY 

Pollination   of  Flowers. — As  soon  as   flowers  come,  observe   them 
closely  and  note  which  have  many  insect  visitors,  and  which  few  or  Done. 
Fill  out  a  report  as  suggested  below  and  add  any  points  which  int< 
you  further. 


1 

E- 

fc> 

V. 

XI 

o 

H 

< 

L- 

t> 

C5 

* 

n 

O 
fa 

an 
Z, 

O 

O 

es 

o 

ao 
O 

o 

o 

a 

S5 
O 
PS 
H 

« 

55 

O 
M 
H 

n 

O 

3 

n 

Z 

si 

< 

V. 

- 

H 
O 

> 

< 

00 

: 

- 

00 

00 

- 
- 
H 

oo 

R 

- 
- 

o 
►4 

OS 

Q 

O 

o 

< 

— 

o 

o 

0 

z 

C 

£ 

H 

Sweet  pea     . 

Dandelion    . 

Hepatica 

Buttercup    . 

224.  Cross-  and  Self-Pollination.  —  All  plants  which  re- 
ceive pollen  from  another  plant  of  the  same  kind  arc  said 
to  be  cross-pollinated.  Darwin  found  that  {»lants  which 
grow  from  seeds  resulting  from  cross-pollination  produce 
a  greater  number  of  seeds  and  that  these  seeds  have  more 
vigorous  embryos  than  those  resulting  from  self-pollina- 


306 


TYPICAL   FLOWERING   PLANTS 


tion.     Since  this  has  been  known,  nursery  men  and  gar- 
deners   have    taken    advantage    of    cross-pollination    to 

improve  their  stock 
and  to  produce  new 
varieties  of  fruits  and 
vegetables.  Much  of 
Luther  Burbank's 
wrork  has  been  based 
on  cross-pollination. 

Plants  have  a  num- 
ber of  devices  for  pre- 
venting self-pollina- 
tion. The  anthers, 
for  instance,  may  be 
turned  away  from  the 
stigma  ;  or  the  pistil 
may  be  so  tall  that 
no  pollen  can  get  on 
it  from  the  stamens  of  the  same  flower;  or  the  stigma 
may  be  ripe  and  the  ovules  started  to  develop  before 
the  stamens  of  the  flower  are  ready  to  shed  their  pollen 
(Figure  317). 

While  it  is  the  rule  that  plants  avoid  self-pollination  and 
self-fertilization,  a  few  have  no  other  way  of  producing 


Figure  31 7.  —  Salvia. 

A  flower  in  which  the  stamens  mature  at 
one  time  and  the  pistils  at  another. 


Figure  318.  —  Easter  Lily. 


seeds.     This  is  true  of  cleistoofamous  flowers.     The  one 
or   two   stamens   which   they    develop    contain   sufficient 


POLLINATION 


307 


pollen  to  fertilize  all 
their  ovules,  for  none 
is  lost,  and  the  pistil 
and  stamen  are  placed 
in  such  a  position  that 
pollination  is  sure  to 
occur. 

Other  plants,  as  some 
of  the  lilies,  are  ar- 
ranged for  cross-ferti- 
lization, but  if  that  fails, 
they  can  pollinate  them- 
selves. An  Easter  lily 
at  first  keeps  its  three- 
parted  stigma  carefully 
closed  until  it  is  well 
out  of  the  way  of  the 
anthers  (Figure  318,  a). 
Then  the  stigma  opens 
out,  exposing  its  sticky  surfaces  to  the  air  and  to  insects 
which  may  visit  the  flower  (Figure  318,  h  ).  If  no  pi 'lieu  is 
brought  to  the  stigma,  however,  the  plant  brings  the  pistil 
up  until  the  stigmas  almost  touch  some  of  its  own  anthers 


Figure  319. —  Fruit  of  the  Bean. 
A  pod. 


Figure  320.  —  Fruit  of  the  Corn. 
Kernels  or  grains. 


308 


TYPICAL   FLOWERING   PLANTS 


dry 

capsule 


from  which  pollen  is  received 
for  the  fertilization  of  the  lily's 
own  egg  cells  in  the  ovules 
(Figure  318,  c). 

225.  The  Fruit  of  the  Bean  and 
Corn.  —  In  science  the  term  fruit 
includes  much  more  than  the 
meaning  we  usually  give  it  when 
we  refer  to  apples,  oranges,  or 
berries.  By  fruit  the  botanist 
means  the  ripened  ovary  of  a 
plant  and  its  contents.  The 
first  step  in  the  production  of 
fruit  is  the  pollination  of  the 
stigma  of  a  flower.  Next  comes 
the  fertilization  of  the  egg  cell 
in  the  ovule.  Finally  the  ovule  develops  into  a  seed,  and 
at  the  same  time,  the  ovary  grows  to  protect  and  to  pro- 
vide nourishment  for  the 
seed  until  it  is  mature. 

In  the  bean  plant  the 
pod  begins  to  develop 
from  the  pistil  as  soon  as 
fertilization     has     taken 


Figure  321.  —  Fruit  of  the 
Poppy. 

A  capsule. 


sepals 


Figure  322.  —  Capsule  of 
Violet. 


Figure  323.  —  Chestnuts. 
A  dry  fruit. 


OTHER   FRUITS 


309 


place.     Each  ovule  remains  attached  to  the  pod  until  the 

former  changes  into  a  seed  and  becomes  mat  inc.  In  bean 
pods  and  string  beans,  ovules  are  often  present  which  have 
not  developed  owing  to  a  lack  of  ferti- 
lization of  the  egg  cell.  When  a  bean  pod 
is  ripe,  it  splits  and  sometimes  curls  up, 
thus  helping  to  scatter  the  seeds.  From 
seed  to  seed  again  makes  up  the  life  his- 
tory of  the  plant. 

In  the  corn,  as  in  the  bean,  each  ovule 
develops  into  a  grain  of  corn,  if  the  egg 
cell  has  been  fertilized.  The  ovary  ad- 
heres so  closely  to  the  egg  cell  that  it 
cannot  be  seen  as  a  separate  organ  like 
the  pod  of  the  bean.  All  the  maturing 
grains  of  corn  receive  nourishment  through 
the  cob  to  which  they  remain  attached,  and  they  are  pro- 
tected by  the  modified  leaves  or  husks.  Undeveloped 
ovules  are   sometimes  found  in   ears  of  corn. 


^vA 

/A 

l>'\ 

- 

• 

Figure  324.  — 
Dry  Fruits. 

a,  beechnuts  ; 
b,  acorn. 


Figure  325.  —  Vertical  Section  of 
Apple. 

A  pome. 


Figure  326.-    Cross  Section 
of  Apple. 

A  pome. 


226.    Other  Fruits. — The  ripened  ovary  and  its  contents 
take  many  forms,  so  that  we  have  the   fleshy  fruits,  such 


310 


TYPICAL   FLOWERING   PLANTS 


Figure  327. 


■  Cross  Section  of  Orange. 
A  berry. 


as  the  apple,  or  dry 
fruits,  like  the  bean. 
Pods  and  other  fruits 
which  open  in  a  definite 
way  are  called  dehiscent 
(Latin,  dehisco,  to  split 
open)  fruits.  Poppies, 
pansies,  and  violets  have 
dehiscent  fruits  called 
capsules.  Nuts,  corn,  and 
wheat  are  examples  of 
indehiscent  fruits  (Fig- 
ures 323  and  324). 

Fleshy  fruits  fall  into 
three  groups  :   (1)  pome 

fruits,  apples  and  pears  which  have  the  seeds  in  a  core  in  the 

middle  surrounded  by  a  thick,  fleshy  part  (Figure  325); 

(2)  drupes,  or  stone  fruits  represented  by  the  plum,  which 

has  the  seed  inclosed  in  a  hard  stone  surrounded  by  soft 

pulp;  and  (3)  berries,  fruits  in  which  the  seeds  are  scat- 
tered through  the  pulp,  as  in 

the   grape,   currant,   or   orange 

(Figure    327).      Most    of    the 

fruits  commonly  called  berries 

are   really  collections  of   small 

drupes.    In  the  strawberry  each 

"  seed  "  is  a  fruit,  and  the  fleshy 

substance   is  the  receptacle  of 

the    flower,    which    has    been 

greatly  enlarged.     In  the  case 

of  the  blackberry,  as  well,  the 

receptacle  is  eaten,  for  the  drupes 

cling-  to  it  as  it  is  removed  from 

&  Figure  328.  —  Forms  of  Dehis- 

the  bush.     Melons,  cucumbers,  cent  Fruits. 


SEED   DISTRllirTlOX 


:m 


Figure  329. —  Fruits  with  Hooks. 
Distributed  by  animals. 


pumpkins,  and  squashes 
are  a  special  kind  of 
berry  called  pepo.  Such 
fruits  have  a  hard  rind. 
The  use  of  fruits  to 
plants  is  simply  to  pro- 
tect the  seeds  while  they 
are  maturing,  and  to 
secure  their  distribution 
later.  But  the  fruits  of 
the  cereal  grains  and  of 

beans  furnish  the  highest  form  of  vegetable  food  for  man 
and  domestic  animals.  The  fleshy  fruits,  on  the  other 
hand,  furnish  many  of  man's  luxuries  in  the  way  of  food. 

One  of  the  most  interesting  studies  about  plants  is  how 
their  fruits  may  be  improved  by  supplying  the  best  possi- 
ble conditions  for  their  growth;  how  their  flavor  may  be 
improved,  the  skins    made  thicker   or  thinner,  t lie  seeds 

grown  larger  or  smaller, 
or  such  other  chang 
made  as  to  cause  the 
fruits  to  be  more  de- 
sirable to  man.  Many 
of  these  changes  may  be 
brought  about  through 
cross-fertilization. 

227.  Seed  Distribution. 
—  Seeds  must  be  scat- 
tered or  distributed  to 
"  spread  "  the  plant,  and 

the     fruit     helps     to     do 

this.      It'   all    the   seeds 
merely  fell  to  the  ground 

Figure  330.— Burdock  in  Blossom.         and     germinated      there, 


312 


TYPICAL  FLOWERING  PLANTS 


Figure  331.  —  Fruits  Distributed 
by  Wind. 


but  little  range  would 
be  added  to  the  plant's 
territory,  and  a  small 
increase  in  the  number 
of  plants  would  take 
place.  Such  plants  as 
the  dandelion  and  bur- 
dock have  developed  the 
most  successful  means 
for  gaining  the  distri- 
bution of  seed,  and 
are,  therefore,  the  most 
common   and   most   widely    distributed. 

Seeds  may  be  distributed  by  an  explosion  of  the  fruit 
case  or  through  the  agency  of  the  wind,  water,  or  animals. 

Some  plants,  like  the  witch- 
hazel  or  jewel- weed,  have  a  fruit 
the  tissue  of  which  is  so  strained 
at  the  time  of  ripening  that  the 
seed  case  bursts  with  an  explo- 
sion which  throws  the  seeds  some 
distance  from  the  parent  plant. 


Figure  332.  —  Other  Fruits 
Distributed  by  Wind. 

a,  catalpa  ;   b,  dandelion  ; 
c,  milkweed. 


Figure  333.  —  Fruits  and  Seeds. 


SEED   DISTRIBUTIOX 


313 


Frequently  plants  de- 
velop special  structures 
which  help  to  secure  the 
distribution     of     seeds 
through   the   agency   of 
an  animal.     Fruits  like 
the     burdock,     for     ex- 
ample, are  provided  with 
hooks  which  catch  firmly 
to  a  passing  animal,  and 
the  fruit  is  carried  lomr 
distances      before      the 
seeds      are     dropped. 
Other    fruits,    like    the 
cherry,  have   an   edible 
pulp   which  causes    the 
fruit    to    be    picked   up 
and    carried    away.     A 
bird   may  fly   with   the 
fruit   to    a    fence    post, 
and  there  eat  the  pulp 
and  drop  the  seed.     In 
many    cases,    as   in    the 
raspberry,     the     whole 
fruit    is   eaten,   but  the 
seeds    are     indigestible 
and  are  carried  far  from 
the  parent  plant  before 
they  are  thrown  out  by 
the  animal. 

Other  fruits  are  fitted 
for  distribution  by 
water.  In  such  cases 
the  fruit  is  surrounded 


Figure  334.  —  Milkweed  Plant. 
Distributing  seeds. 


Figure  335. —  Seed  of  Cotton. 


314 


TYPICAL   FLOWERING   PLANTS 


by  a  light,  buoyant  substance,  as  in  the  bur  reed  and  the 
cocoanut,  and  so  may  be  carried  hundreds  of  miles  without 
injury.  In  the  case  of  still  other  fruits,  like  grains,  the 
whole  fruit  is  eaten,  but  enough  are  produced  by  the  plant 
so  that  many  may  be  destroyed  and  yet  some  be  left  to 
serve  as  seed,  and  thus  prevent  the  plant  from  becoming 
extinct.  Squirrels,  in  storing  up  food  for  the  winter  often 
bury  nuts  which  are  not  used,  and  some  of  these  are  sure 
to  grow. 


LABORATORY   STUDY   OF   SEED   DISPERSAL 

Every  season  of  the  year  affords  material  for  this  phase  of  plant  study. 
Record  your  result  as  follows  : 


Agencies 

Devices 

r. 

a> 

-d 

3 

"ci 

"35 

CO 

M 

3 

.£   O 

6 

£ 

c3 

< 

o 
y, 

r-r! 

P 

n 

c 

-3 

^ 

Dandelion  .     .     . 

Maple    .... 

Burdock      .     . 

Cherry  .... 

Etc 

228.  The  Struggle  for  Existence.  —  In  the  process  of  dis- 
tribution, six  or  eight  seeds  from  a  plant  may  fall  in  al- 
most exactly  the  same  place.  It  is  probable  that  all  will 
begin  to  grow,  but  only  one  or  two  will  live,  because  there 
will  not  be  sufficient  light,  food,  or  moisture  for  all.  In 
this  case  the  plants  which  get  the  best  start  or  have  the 
most  vigor  crowd  out  the  others.  In  biology  this  effort 
to  secure  the  conditions  necessary  for  life  is  known  as  the 
struggle  for  existence.  The  result  of  this  struggle  is  spoken 
of  as  the  survival  of  the  fittest. 


ENEMIES   OF    THE  BEAN 


3 1 5 


Figure  336.  —  Bean  Plant 
Injured  by  Bacteria. 


229.    Enemies  of  the  Bean.  —  Besides  this  struggle  to  gel 
its  share  of  light,  food,  and  moisture,  the  bean   plant  has 

to  contend  with  enemies.     One 

enemy  is  a  plant  or  bacterium 

(Chapter   XXI II)   which   lives 

upon  the   tissues   of    the   bean. 

This  bacterium  causes  the  dis- 
ease known  as  bean  blight,  one  of 

the  most  destructive  diseases  of 

beans,  and  one  which  scientists 

have  been  unable  to  prevent  or 

cure.     The  plants  having  bean 

blight  appear  wilted,  and  have 

clear  watery  spots  in  the  leaves 

which,  after  a  time,  turn  brown, 

dry  up,  and  drop  out,  leaving  a  hole  in  the  leaf  where 

each   spot   was.     The   bacteria  which  cause   the   disease 

enter  through  the  stomata,  appear  first  in  the  cotyledons, 

then  work  into  the 
stem,  and  finally  kill 
the  plant  by  stopping 

up  the  sap  tubes.  The 
bacteria  arc  carried  by 
insects  from  one  plant 
to  another. 

Any  insect  which 
carries  these  bacteria 
is  indirectly  an  enemy 
of  the  bean  plant,  hut 
bean  weevils  injure  it 

directly  (  Figure  337  >. 

The  female  weevil 
gnaws  holes  through  the  young  pod  and  pushes  her  eggs 
into  the  pod  or  into  the  young  beans.      The  eggs  develop 


Figure  337.  —  Beans  Damaged  by  Weevils. 


316  TYPICAL   FLOWERING   PLANTS 

into  grubs  or  larvae,  which  get  their  food  from  the  sub- 
stances of  the  bean  seed.  If  the  grubs  mature,  the  weevils 
may  craAvl  out,  thus  leaving  large  holes  in  the  bean.  The 
loss  to  the  farmer  comes  not  only  in  the  food  actually  eaten 
by  the  weevils,  but  also  in  spoiling  the  beans  as  food 
for  man. 

If  the  pods  show  that  the  beans  have  been  pierced  by 
weevils,  the  development  of  the  eggs  can  be  prevented  by 
storing  the  beans  in  a  cold  place.  A  test  for  the  presence 
of  weevils  is  to  place  the  beans  in  water,  where  those  that 
contain  Aveevils  will  float. 

230.  Enemies  of  Corn.  —  One  great  enemy  of  corn  is  a 
fungus  (see  page  360)  called  corn  smut.  This  fungus 
destroys  the  corn  kernels  by  living  on  the  food  in  them 
and  filling  the  whole  kernel  with  black,  sticky  spores. 

Grasshoppers  injure  the  corn  plant  by  eating  the  leaves, 
and  plant  lice  by  sucking  its  juices. 

In  speaking  of  an  animal  as  a  friend  or  an  enemy  of  a 
plant  or  of  man,  we  should  remember  that  every  plant  and 
animal  is  only  endeavoring  to  maintain  its  own  life.  We 
regard  them  as  enemies  when  they  destroy  or  injure  some- 
thing which  we  are  trying  to  raise  to  maintain  our  own 
lives,  and  as  friends  when  they  destroy  our  enemies. 

231.  The  Raising  of  Beans.  —  Beans  are  raised  in  large 
quantities  for  food.  In  New  York,  Michigan,  and  California 
more  than  nine  million  bushels  were  raised  in  the  year  1915. 
Michigan  raised  four  and  a  quarter  million  bushels,  and 
New  York  one  and  a  quarter  million  bushels. 

A  crop  of  beans  can  be  planted,  cultivated,  harvested, 
and  threshed  by  tools  and  machinery.  But  before  beans 
can  be  used  as  food  they  must  be  examined  by  some  one 
so  that  all  those  discolored  or  specked  by  weevils  may  be 
discarded.  Beans  unfit  for  human  food  can  be  eaten  by 
such  animals  as  hogs  and  sheep.     So  we  find  that  where 


HISTORY   OF  BEAN   PLANT  'Ml 

the  raising  of  beans  is  an  important  industry,  the  raising 
of  hogs  and  sheep  is  also  practiced  extensively.  Sheep  eal 
not  only  the  rejected  dry  beans,  but  also  the  pods. 

Certain   varieties  of  beans  are   eaten  when  young  and 

«  I 

green,  the    pod   itself   being  used  as   an  article  of  food. 


Figure  338.  —  A  Field  of  Beans. 

These  "string  beans"  are  raised  extensively  in  some 
localities  and  are  canned  for  the  market.  In  this  industry 
much  of  the  work  has  to  be  done  by  hand. 

232.  The  Value  of  Beans  as  Food.  —  Beans  furnish  more 
protein  and  yield  more  energy  than  any  other  kind  of  plant 
food  except  wheat.  Compared  with  the  cost  of  meal  or  of 
eggs,  vegetable  forms  of  protein  are  much  cheaper,  and 
beans  are  the  cheapest  of  all.  String  beans  do  not  contain  so 
much  nourishment  as  dry  beans.  Beans  properly  cooked 
are  both  digestible  and  palatable  and  should  form  an  even 
more  important  part  of  our  diet  than  at  present. 

233.  History  of  the  Bean  Plant.  —  The  bean  and  the  mem- 
bers of  the  bean  family  (beans,  peas,  clover)  are  known  to 
have  been  cultivated  from  the  earliest  times  .>!'  human 
history.  They  are  spoken  of  in  the  Bible  under  the  name 
of  pulse  (Daniel  i.  12),  and  mention  is  made  of  them  in  the 
records  of  the  Kgyptians,  (i  reeks,  and  Roman8.  When 
America  was  discovered,  the  Indians  were  cultivating  pole 


318 


TYPICAL   FLOWERING  PLANTS 


beans.     Beans  are  now  widely  distributed,  one   or  more 
varieties  being  grown  in  all  temperate  regions. 

The  value  to  the  soil  of  the  plants  of  the  Pulse  family 
has  long  been  known,  bat  the  reasons  for  it  have  not  been 
understood  until  recently.  As  we  have  seen,  bacteria  in 
the  roots  of  beans  gather  nitrogen  which  goes  to  replace 
that  drawn  from  the  soil  by  other  plants.     Soils  which 

lack    nitrogen    may    be 


improved  by  growing 
on  them  a  crop  of 
the  pulse  family  and 
then  plowing  it  under. 
This  method  of  enrich- 
ing the  soil  is  known 
as  " green  manuring." 
See  page  270. 

The  bean  family  in- 
cludes such  well-known 
plants  as  peas,  peanuts, 
clover,  and  alfalfa.  The 
peanut  has  the  peculiar 
habit  of  thrusting  its 
blossoms  into  the  ground  after  they  have  been  polli- 
nated. The  pods  mature  there  and  are  harvested  by 
digging. 

234.  The  Raising  of  Corn.  —  Most  of  the  work  of  planting, 
cultivating,  and  harvesting  corn  is  done  by  machinery. 
Hand  work  is  necessary  only  in  removing  the  ears  from 
the  stalk  and  the  husk  from  the  ears.  Because  corn  is  so 
valuable  a  food  for  men  and  animals  and  because  so  much 
of  the  work  necessary  in  raising  it  can  be  done  by  machin- 
ery, corn  raising  has  become  one  of  the  most  important 
industries  on  the  easily  cultivated  level  prairies  of  the 
Middle  West. 


Figure  339.  —  Peanuts. 


THE  RAISING  OF   CORN 


319 


z 
c 

p 
o 

D 
Q 
O 

a. 
Qu 

2 
O 

O 

u. 
o 

a. 
< 


5 

CO 

D 
O 


320  TYPICAL   FLOWERING   PLANTS 

235.  History  of  the  Corn  Plant.  —  The  corn  plant  was 
found  growing  in  America  when  the  New  World  was 
discovered,  and  it  was  one  of  the  principal  foods  of  the 
Indians.  Now  corn  is  grown  wherever  the  climate  is  not 
too  cold  for  it  to  come  to  maturity. 

236.  Economic  Importance  of  Plants.  —  From  a  biological 
point  of  view  much  of  the  study  of  plants  is  concerned  with 
the  life  of  the  plant  itself,  considered  as  an  organism; 
what  its  problems  are,  and  what  peculiarities  it  has  devel- 
oped which  have  aided  it  in  the  struggle  for  existence. 
There  is,  however,  another  point  of  view,  —  the  importance 
of  plants  to  man  as  the  source  of  his  food  supply.  Within 
recent  years,  this  has  come  to  be  more  fully  recognized 
than  ever  before,  and  as  a  result,  agriculture  as  an  industry 
has  been  almost  revolutionized  by  the  application  of  scien- 
tific methods. 

Man  has  learned  to  take  a  wild  plant  and,  by  cultivation, 
selection,  and  cross-pollination,  to  improve  any  part  of  the 
plant  he  wishes.  Man  is  the  only  animal  intelligent  enough 
to  do  this,  and  his  success  depends  upon  his  following  such 
natural  laws  as  he  has  been  able  to  discover.  Students  are 
constantly  endeavoring  to  learn  the  conditions  under 
which  each  plant  thrives  best,  —  the  kind  of  food,  soil- 
temperature,  amount  and  kind  of  cultivation;  what  dis- 
eases it  is  likely  to  have,  and  how  to  prevent  and  cure 
them. 

SUMMARY   OF   THE   BEAN 

The  bean  is  a  typical  flowering  plant  and  is  represent- 
ative of  the  dicotyledons.  The  bean  seed  contains  an 
embryo  which  is  nourished  by  the  food  in  the  cotyledons. 
A  bean  plant  has  roots  to  hold  it  firmly  in  place  and  to 
gather  the  water  which  contains  part  of  the  plant's  food. 
It  has  a  stem  to  hold  the  leaves  to  the  light  and  air,  and 


SUMMARY   OF   CORN  321 

to  carry  water  and  food.     The  Leaves  are  the  pari  of  the 

plant  where  most  of  the  vital  processes  are  carried  on. 
The  vital  processes  which  occur  in  the  leaf  are  respiration, 
photo-synthesis,  or  the  making  of  food,  excretion,  and 
assimilation. 

The  bean  flower  contains  the  organs  necessary  for  re- 
production. A  seed  is  formed  when  the  nucleus  of  a 
pollen  grain  unites  with  the  nucleus  of  the  egg  eel]  in  tin- 
ovule.  The  fruit  of  the  bean  is  the  pod  which  contains 
the  seeds.  The  bean  depends  upon  insects  for  cross- 
pollination. 

The  raising  of  beans  is  an  important  industry.  Beans 
probably  once  grew  wild,  but  now  they  are  widely  culti- 
vated. Their  chief  value  as  food  is  due  to  the  large  amount 
of  protein  in  the  seed. 

A  bean  plant  which  has  successfully  completed  its  life 
work  has  added  to  the  sum  total  of  the  solid  matter  on 
earth,  and  has  left  stored-up  material  which  may  be  used 
either  as  food  for  animals  or  for  the  new  plant  which 
the  seed  contains.  The  plant  has  added  to  the  supply  of 
oxygen  in  the  air,  and  by  decomposition  through  the  aid 
of  bacteria  leaves  the  soil  richer  in  nitrogen. 

SUMMARY  OF  THE   CORN 

The  corn  is  a  typical  monocotyledonons  plant.  Food  for 
the  embryo  is  stored  at  one  side  of  the  grain.  This  embryo 
is  supplied  with  food  prepared  in  a  modified  cotyledon. 
A  corn  plant  has  many  roots,  all  of  about  the  same  size. 
which  srather  for  it  water  and  inorganic  matter  and  hold 
the  plant  in  the  soil.  In  addition  to  the  regular  loots, 
there  are  prop-roots.  The  leaves  of  coin  have  parallel 
veins  and  clasping  bases.  The  leaves  perform  most  of  the 
vital  processes  of  the  plant.      The  stem  has  a  hard  rind  and 


322  TYPICAL   FLOWERING  PLANTS 

scattered  fibro-vascular  bundles.  The  fruit  consists  of 
grains  in  which  the  ovary  adheres  closely  to  the  seed. 
Corn  depends  upon  the  wind  for  pollination.  The  stamens 
are  in  the  tassels  and  the  style  of  the  pistil  is  the  silk.  It 
is  a  monoecious  plant. 

QUESTIONS 

How  does  the  bean  plant  begin  life  ?  Explain  the  work  of  each  part  of 
the  plant.  What  is  the  importance  of  photo-synthesis  ?  What  is  the  dif- 
ference between  pollination  and  fertilization  ?  Why  are  beans  valuable  ? 
What  is  a  food  ?  How  can  you  show  that  any  given  substance  is  a  food  ? 
How  do  roots  help  the  leaves  ?  How  do  the  stems  help  the  leaves  ? 
Compare  the  corn  plant  with  the  bean  in  structure,  importance,  etc. 

REFERENCES 

Campbell,  University  Textbook  of  Botany,  p.  9. 

Coulter,  Barnes  and  Cowles,  Vol.  I,  pp.  363-380. 

Kellogg,  The  Animals  and  Man,  Chapter  15. 

Leavitt,  Outlines  of  Botany.     Roots,  pp.  26-44. 

MacDougal,  Enzymes,  pp.  173,  265,  274. 

Needham,  General  Biology,  pp.  7-33. 

Sedgwick  and  Wilson,  Biology,  Chapter  I. 

U.  S.  Department  of  Agriculture  Bulletins. 

Coulter,  Plant  Life  and  Plant  Uses,  Chapters  1,  2,  4,  5,  6,  7,  8. 


CHAPTER    XX r 


OTHER   FLOWERING   PLANTS 


237.  The  Flowering  Plants. — True  flowering  plants  are 
the  most  highly  developed  of  all.  They  arc  numerous, 
it  being  estimated  that 
there  are  120,000  kinds. 
Some  varieties  are  so 
small  as  hardly  to  be 
noticed,  while  others, 
like  the  hardwood  trees, 
are  very  large.  Some 
live  submerged  in  the 
water,  while  others  are 
found  only  in  deserts. 

The  flowering  plants 
are  of  special  interest 
on  account  of  their  in- 
timate relation  to  our 
daily  life,  and  on  account 
of  this  close  relationship 
we  should  study  some 
of     the    most     common 


Figure  341.  —  Walnut  Tree. 


families,  such  as  the  grass,  rose,  mustard,  and  the  like,  all 
of  which  are  easily  recognized. 

The  Grans  Family.  — The  grass  family  has  long  narrow 
leaves  with  clasping  bases  and  parallel  veins,  fibrous 
roots,  and  inconspicuous  flowers  which  are  pollinated  by 
the  wind.      The  grasses  arc    the  most    important    of   all 

323 


324 


OTHER   FLOWERING   PLANTS 


(A 
H 
< 

o 

u. 

o 

O 

H 
O 

Q 
O 

cu 

It 
o 

< 


ON 
CO 
U 

a: 
o 


OTHER   FLOW K RISC   PLANTS 


325 


2 
O 

H 
O 

D 
Q 
O 

a, 
2 

r 

u. 
o 

a. 
< 


a 


326 


OTHER   FLOWERING  PLANTS 


Figure  344. — The  Cereals. 
a,  wheat;   b,  oats;  c,  barley;   d,  rye. 

plants  as  food  for  man  and  the  animals  which  he  uses. 
This  family  includes  corn,  wheat,  oats,  barley,  rye,  rice, 
and  similar  grains.     Wheat  and  barley  are  mentioned  in 

the  earliest  literature  and  were  among 
the  first  plants  cultivated  for  food.  As 
men  learned  to  till  the  soil  and  harvest 
these  grains,  agriculture  became  estab- 
lished and  a  marked  step  towards  civili- 
zation was  made.  In  China  and  India 
millions  to-day  depend  very  largely  upon 
rice.  In  1915  the  United  States  pro- 
duced 3,054,535,000  bushels  of  corn, 
1,011,505,000  bushels  of  wheat,  and 
28,974,000  bushels  of  rice. 

Lily   Family. — Lilies  have  parallel- 
veined   leaves.     The    flowers  are  made 

Figure  345    -Lily-     uP  °^  a  six-parted  perianth  (calyx  and 
of-the-Valley.         corolla  taken  together),  six  stamens,  and 


THE   CROWFOOT   FAMILY 


327 


Figure  346.  —  X-ray  of  Easter  Lily. 


a     three-parted      pistil. 

The  fruit  is  a  capsule. 

Lilies      are      cultivated 

chiefly     for     decorative 

purposes. 

W<dnut  Family. — The 

trees     of     this     family 

furnish  us  with  nuts  and 

valuable    lumber.      The 

monoecious    flowers    are 

grouped  in  catkins.   The 

leaves  are  alternate  and 

pinnately        compound. 

All     the    walnuts     and 

hickories  belong  to  this  very  useful  family  (  Figure  341  ). 
Beech  Family.  —  Like    the    walnut    family,  this    uri""p 

consists  of  trees,  of  which  the  beech,  oak,  and  chestnut 

are  the  most  common.     All  are  valuable  for  lumber  and 

firewood.     The  leaves  are  simple,  alternate,  and  straight- 
veined.      The   flowers   are    monoecious. 

Crowfoot  Family.  — 
This  large  family  is  valu- 
able to  US  for  tin'  medi- 
cines (mostly  poisonous") 
which  it  furnishes.  The 
medicinal    members    <>t 

this  family  arc  hydrast  is, 

aconite,  hellebore,  and 
Larkspur  ;  while  other 
members,  as  clematis, 
peony,  and  columbine, 
arc  cultivated  for  orna- 
ment.       The     common 

Figure  347. —  Leaves  and  Bud  of  Beech,     buttercup     shows     most 


328 


OTHER   FLOWERING   PLANTS 


Figure  348.  —  Wild  Columbine. 


Figure  349.  —  Stamens  and 
Pistils  of  Rose. 


of  the  characteristics  of 
the  crowfoot  family. 
The  leaves  are  commonly 
dissected ;  the  petals, 
sepals,  and  pistil  are  all 
disconnected.  The  juice 
of  the  buttercup  is  color- 
less and  is  biting  to  the 
taste. 

Mustard  Family.  — 
Garden  vegetables  such 
as  the  turnip,  radish, 
cabbage,  horse-radish, 
and  mustard  belong  to 
this  family.  All  have 
regular  flowers  consist- 
ing of  four  sepals,  four 
petals,  and  six  stamens. 
The  corolla  is  in  the 
form  of  a  Greek  cross. 
These  plants  have  a 
pungent,  watery  juice 
which  is  non-poisonous.  The 
fruit  is  a  kind  of  pod  called  a 
silique. 

Rose  Family.  —  The  flowers 
are  regular  with  the  calyx  usually 
of  five  sepals  and  the  corolla  of 
five  petals.  The  leaves  are 
alternate  and  usually  serrate  on 
the  edge.  The  rose  family  is  as 
important  in  furnishing  the 
luxuries  of  our  food  as  the  grass 
family  is  for  the  necessaries.    To 


THE   PARSLEY    FAMILY 


329 


this  group  belong  all  of  the  common  orchard  fruits,  such  as 

apples,  peaches,  and   plums,  and   many   of    the   common 

berries,  such  as  the  raspberry  and 

strawberry.     Many  of  the  members 

of  this  family  are  also  cultivated  for 

ornament. 

Pulse  Family.  —  Beans,  peas, 
vetch,  alfalfa,  peanuts,  clover,  and 
the  like  are  members  of  this  family. 
These  plants  may  be  recognized  by 

their  irregular,  papiliona- 
ceous   flowers,    alternate 

leaves  with  stipules,  and 

by  their  having  the  fruit 

in    the    form    of    a   pod. 

This  family  furnishes  us 

with  most  of  our  vesre- 

table  protein  food.     The 

plants   improve   the   soil 

by    the    aid    of    bacteria.    Figure  350.  —  Rose  Flower 
Wisteria,    red    bud,    and       Turning  into  a  Fruit. 
the  locusts  are  cultivated      <*>  early  staSe ;  *>,  later 
for  ornamental  purposes. 

Flax  Family.  —  While  this  is  not  a  large 
family,  yet  it  furnishes  all  of  our  Linen.  Flax 
rarely  grows  wild,  but  requires  cultivation. 

Mallow  Family.  —  This  family  is  also  impor- 
tant in  furnishing  material  for  cur  clothing,  as 
the  cotton  plant  belongs  here.      Hollyhock  and 
Figure  351.  althsea  are  forms  cultivated  for  ornament. 
of  Rose/         Parsley  Family.  —  This  family  includes  such 
garden    vegetables    as    parsnip,    parsley,    and 
carrots,  and  plants  like  fennel,  dill,  coriander,  and  caraway 
used  for  medicine  and  for  flavoring  food.       These  plants 


**i 


^ 


330 


OTHER   FLOWERING   PLANTS 


THE  NIGHTSHADE   JAMIL) 


331 


have  hollow,  ribbed  stems;  alternate,  compound    leav<    . 
and  flowers  in  an  umbel.     See  Figure  308. 


Figure  353.  —  Stipules 
of  Rose  Leaf. 


Figure  354.  —  Flower  of 
Mallow. 


Mint  Family. — The  members  of  this  family  are  easily 
recognized  by  their  square  stems,  opposite  leaves  with 
crenate  margins,  and  bila- 
biate flowers  (an  irregu- 
lar flower  divided  into 
two  parts).  Peppermint, 
spearmint,  catnip,  hore- 
hound,  pennyroyal,  sage, 
savory,  and  thyme  are 
some  of  the  mints  used 
for  medicine  and  in  food. 

Nightshade  family.  — 
Here  are  found  many 
poisonous  plants,  as  to- 
bacco and  Jimson  weed 
from  which  stramonium 
(similar  to  belladonna 
but  more  powerful)  is 
obtained.  The  tomato, 
potato,  and  egg-plant 
are  used  for  food. 
Petunias    are    cultivated  Figuke  355.-    Water  Huklh.und. 


332 


OTHER   FLOWERING  PLANTS 


2 

O 

o 

D 
O 

Ou 

2 

O 

H 
O 

O 

u. 
o 

< 


CO 
UJ 

o 


6 

£ 
H 


THE   NIGHTSHADE   FAMILY 


333 


Figure  357.  —  Self-heal 
A  common  weed. 


5          ..  A  ' 

5*  7» \V  '  - .                 f* 

HA    i 

.  •* 

MSfn^      •  x 

Figure  358,  —  Hedge  Nettle. 


334 


OTHER   FLOWERING   PLANTS 


Figure  359.  —  Common  White  Daisy. 


for  ornament.  The  foliage  of  all  these  plants  is  rank- 
scented,  the  leaves  are  alternate,  and  the  flower  five- 
parted. 

The  Composite  Family.  —  This  family  is  typified  by  the 
common  daisy  and  dandelion.  They  have  their  flowers  in 
heads  and  are  of  two  kinds,  ray-flowers  and  disk-flowers. 

This  is  one  of  the  largest 
families  of  plants,  and 
from  the  standpoint  of 
the  botanist,  the  most 
complex.  It  contains 
our  common  weeds,  such 
as  the  daisy,  dandelion, 
golden  rod,  aster,  bur- 
dock, thistle,  and  hawk- 
weed. 

Not  all  the  flowering 


\y 


1 


Figure  360.  —  Dandelion. 


THE   COMPOSITE    FAMILY 


335 


336 


OTHER   FLOWERING   PLANTS 


plants  are  beneficial  to  man,  and  every  farmer  and  gardener 
has  to  struggle  with  the  weeds.1     Some  of  the  members 

of  the  composite  family, 
like  the  goldenrod  and 
daisy,  lend  a  charm  to 
the  fields,  and  many 
people  dislike  to  think 
of  them  as  obnoxious 
plants.  But  they  pre- 
vent the  grass  from 
growing,  and  cattle  will 
not  eat  them  either  in 
the  winter  or  in  the 
summer,  so  that  they  are 
a  nuisance  to  the  farmer. 
A  weed,  then,  may  be 
defined  as  a  plant  which 
interferes  with  the 
growth  of  some  useful 
plant.  Weeds  are  suc- 
Figure  362.  —  Canada  Thistle.  cessful     in    growing    and 

in  living,  because  they 
have  strong  roots,  produce  many  seeds,  and  have  numer- 
ous devices  for  distributing  their  seeds. 


SUMMARY 

The  flowering  plants  are  the  most  highly  developed  of 
all  the  plants  and  bear  an  intimate  relation  to  mankind. 
The  many  grasses  and  cereals  furnish,  animals  and  man 
with  much  of  their  food.  The  cultivation  of  these  plants 
has  aided  the  development  of  civilization. 

1  Thompson,  "Distribution  of  Weeds  by  Means  of  Farm  Seeds."  School 
Science  and  Mathematics,  December,  1915,  page  770.  Georgia,  A  Book  of 
Weeds- 


Ql'KSTlOXS  33' 


QUESTIONS 

What  plants  furnished  part  of  your  f<>« >< J  t < »-<l;iy  ?  In  what  part  of  tin- 
plant  was  this  food  made?  In  what  part  stored?  What  fruits  do  you 
eat?  Which  plants  jjrow  these  fruits?  Where  <l"  these  plants  lii 
Name  plants,  parts  <>f  which  are  used  in  medicine.  What  plants  are  u-  'I 
in  making  paper?  What  parts  of  a  plant  are  used  in  making  hous* 
What  kinds  of  cloth  are  made  from  cotton?  from  linen?  from  .-ilk? 
from  wool  ?     What  are  the  common  weeds  ? 


CHAPTER   XXII 


THE  SIMPLEST  PLANTS 


238.  Introduction.  —  Many  plants  when  full  grown  never 
have  mere  than  one  cell  and  are  so  small  that  they  can 
be  studied  only  through  a  microscope.  All  of  these 
minute  plants  have  long  scientific  names,  often  hard  to 
remember,  but  they  are  the  same  names  which  the  English, 
German,  or  Japanese  children  have  to  learn  when  they 
study  these  plants. 

The  two  plants  discussed  in  this  chapter  belong  to  the 
group  known  as  the  Green  Alyce  (Latin,  algce,  seaweed). 

The  names  of  these  two  plants 
are  Pleurococcus  (plu-ro-kok'iis) 
and  Spirogyra  (spi-ro-ji'ra). 

We  are  now  to  compare  these 
microscopic  plants  with  the  bean 
plant  with  its  many  parts  com- 
posed of  hundreds  of  cells,  which 
is  able  to  respire,  make  its  own 
food,  and  grow  bean  seeds. 

239.  Pleurococcus. — Pleurococ- 
cus is  a  widely  distributed, 
single- celled  plant  which  grows  in  great  abundance 
upon  the  shady  side  of  trees,  old  buildings,  and  rocks. 
After  a  rain  it  is  conspicuous  in  these  places  as  green 
patches.  A  bit  of  this  green  substance  examined  with 
a  microscope  shows  many  green  cells.  Each  plant,  or 
we  may  say,  each  cell  is  a  somewhat  roundish  structure 

338 


Figure  363.  —  Pleurococcus. 

a,  single  cell;   b,  cell  dividing; 
c  and  d,  groups  of  cells. 


SPIROGYRA  339 

with  a  clearly  defined  cell  wall.  The  contents  <>f  the  cell 
are  green,  due  to  the  chlorophyll  which  conceals  all  parts  «»t' 
the  cell  except  the  nucleus.  Tin;  nucleus  usually  li«-^  uear 
the  center  of  the  cell.  As  lun«r  as  the  cell  is  full  of  chlo- 
rophyll,  the  cytoplasm  cannot  be  Been  (  Figure  363). 

Pleurococcus  makes  its  own  food  as  tic  bean  does,  ami 
apparently  it  is  able  to  digest  the  starch  and  protein  which 
it  makes  in  a  manner  similar  to  that  of  the  bean.  When- 
ever a  number  of  pleurococcus  cells  are  examined,  some 
are  found  to  be  dividing.  In  this  division  the  nucleus 
forms  two  nuclei  which  move  apart.  A  partition  wall 
forms  and  two  cells  take  the  place  of  the  old  or  parent 
cell.  This  method  is  called  fission  (Latin,  Jixsn*\  cleft  ), 
and  is  the  simplest  form  of  reproduction.  In  pleurococcus 
the  cells  do  not  always  separate  at  once,  but  form  groups 
of  two,  three,  or  four  cells  (Figure  363). 

SUMMARY 

This  simple  unicellular  (one-celled)  green  plant,  pleu- 
rococcus, lives  and  makes  its  own  food  and  grows  new 
cells.  While  there  are  no  flowers  and  seeds  as  in  tie- 
bean,  yet  this  plant  is  able  to  reproduce  itself.  All  of 
the  important  life  processes  found  in  the  bean  take  place 
in  the  simple,  single  cell. 

LABORATORY   STUDY    OF    PLEUROCOCCUS 

Study  this  as  an  example  of  a  plant  which  consists  of  a  Bingle  cell, 
but  still  performs  all  the  processes  common  t.>  higher  plants.  Soak  :i  bit 
of  bark  and  scrape  it  ucntly  to  ^et  the  pleurococci  cells,  some  ot  which 
may  be  in  groups.     Draw  a  single  cell  ami  a  group  of  .ells. 

240.    Spirogyra. — This  plant  is  best  known  as  the  "pond 

scum "  which  l;to\vs  in  most  fresh  water  ponds  and  in 
slow  running  streams.  It  may  be  kepi  for  some  time  in 
glass  dishes  in  a  laboratory.     Instead  of  being  made  up  of 


340 


THE  SIMPLEST  PLANTS 


single  cells  or  clusters  of  cells,  the  cells  of  spirogyra  are 
cylindrical  in  shape  and  are  attached  end  to  end.  This 
results  in  long,  fine  threads  which  float  in  the  water  in 


large  masses. 


The  individual  cells  of  spirogyra  are  provided  with  one 
or  more  narrow  green  bands  arranged  spirally  within  the 


t" — r""1-?^  |fT;-;T)^^»J•<v^:v■■."-■■^ 


v^~ 


<hJ 


Figure  364,  —  Spirogyra. 

protoplasm.  These  spiral  bands  of  chlorophyll  are  the 
special  structures  which  manufacture  food  (Figure  364). 
The  cells  of  the  filament  increase  rapidly  in  size  and  di- 
vide, and  thus  the  filaments  increase  in  length.  As  each 
cell  divides,  the  cell  wall  grows  in  at  right  angles  to  the 
length  of  the  plant.     Spirogyra  grows  so  rapidly  in  the 

spring  that  in  a  short 
time  the  water  may  be- 
come polluted.  The 
bubbles  found  among  a 
mass  of  spirogyra  are 
the  oxygen  which  the 
cells  give  off  during 
photosynthesis. 

During  the  summer 
there  are  times  when  spirogyra  reproduces  in  another 
manner  (Figures  365  and  366).  Two  cells  of  adjacent 
plants  join  by  putting  forth  tubes  which  fuse  on  meeting. 
The  contents  of  one  cell  pass  through  the  tube,  and  flow 
into  and  unite  with  the  contents  of  the  other  cell.  Thus 
there  is  formed  a  single  roundish  mass  of  protoplasm 
surrounded  by  a  thick  wall.     This  mass   of  protoplasm 


Figure  365.  —  Spirogyra  Conjugating. 


SPIROGYRA 


341 


is  called  a  sexual  spore,  because  two  cells  unite  to  form  it. 
The  two  cells  which  thus  unite  are  called  gametes  and  are 
identical  in  all  their  parts.  This  spore,  therefore,  is  known 
as  a  zygospore  (Greek,  zy<ios, 
yoke;  spora,  seed).  In  the 
formation  of  a  zygospore,  the 
cells  are  joined  permanently  and 
a  form  of  sexual  reproduction 
is  present. 

As  a  zjrgospore,  spirogyra  can 
live  in  a  resting  condition  dur- 
ing periods  unfavorable  to  its 
growth,  as  in  winter  or  during  a 
drought.  When  conditions  again 
become  favorable  the  zygospore 
germinates    and    grows    into    a 

filament.  The  spirogyra  is  able  to  do  the  same  things 
which  a  pleurococcus  does  and  has  the  same  life 
processes. 


Figure  366.  -  -  Microphoto- 
graph  of  Conjugating 
Spirogyra. 


LABORATORY   STUDY   OF   SPIROGYRA 

Notice  :  (1)  the  clear  outer  part  called  the  cell  wall  ;  (2)  the  mail 
mass  of  the  cell,  a  substance  called  cytoplasm.  (This  ran  be  seen  easilj 
by  putting  a  strong  sugar  solution  under  the  cover  glass.  The  cytoplasD 
draws  away  from  the  cell  wall  into  a  compact  mass  in  the  center  of  tin 
cell.)  (3)  The  darker  portion  of  the  nucleus,  in  <>r  near  the  center  01 
the  cell.  (This  can  be  seen  clearly  by  patting  a  drop  of  weak  iodine 
under  the  cover  glass,  using  fresh  material  for  this  test.)  (4)  A  spiral 
band  of  green  coloring  matter,  chlorophyll,  containing  bright  spots. 

Examine  spirogyra  in  a  mass,  floated  out  in  water  in  a  ulass  oron  ;■ 
plate.  Feel  of  it  and  observe  that  it  is  slimy.  Note  its  color  and  delicai 
After  it  has  been  in  the  sun  for  a  lime,  note  the  bubbles  of  gas  entangled 
in  the  spirogyra.  which  help  to  make  it  float  With  a  microscope  • 
amine  filaments  which  are  joined  in  places  by  outgrowths  from  othei 
filaments.  Such  filaments  are  said  to  be  in  conjugation.  Draw  the  out 
growing  tubes,  the  emptj  cell,  ami  the  zygospore  or  zygote. 


342  THE  SIMPLEST   PLANTS 


SUMMARY 


Both  pleurococcus  and  spirogyra  are  called  algae,  and 
each  is  typical  of  many  other  plants  of  the  same  kind. 
Our  chief  interests  in  them  are  that  they  are  adapted  to 
life  in  the  water  from  which  they  obtain  most  of  their  food 
and  that  each  cell  is  capable  of  carrying  on  all  the  life 
processes  for  itself.  Plants  like  pleurococcus  are  called 
unicellular ;  those  like  spirogyra,  which  consist  of  many 
cells  joined  end  to  end  thus  forming  a  strand,  are  called 
filamentous  algce.  Pleurococcus  is  found  on  old  buildings, 
fences,  posts,  rocks,  and  on  the  bark  of  trees.  It  shows 
more  plainly  in  wet  weather  than  in  dry,  for  then  it  is 
growing.  Spirogyra  grows  in  running  water,  attached  to 
objects  on  the  bottom,  or  floats  in  masses  on  the  surface 
of  ponds,  ditches,  and  sluggish  streams.  Neither  of  these 
plants  has  any  economic  value. 

Algae  are  simple  plants  which  grow  in  water  or  in  moist 
places.  Fresh  water  algae  are  usually  small.  Algae  illus- 
trate how  a  plant  cell  carries  on  the  life  processes.  The 
cell  is  the  unit  of  plant  structure,  and  plant  cells  are 
similar  to  animal  cells  in  all  essential  respects. 

QUESTIONS 

What  is  a  cell?  Compare  plant  with  animal  cells.  Explain  the 
process  of  conjugation.  In  what  respects  is  the  formation  of  a  zygospore 
similar  to  the  process  of  fertilization  in  the  bean  ? 

REFERENCES 

Atkinson,  High  School  Botany. 
Bennett  and  Murray,  Cryptogamic  Botany. 
Bergen  and  Caldwell,  Botany. 
Leavitt,  Outlines  of  Botany. 


CHAPTER    XXIII 
THE   SMALLEST   PLANTS    (BAOTEEIA) 

241.  Bacteria.  —  Bacteria  are  the  smallest  of  all  plants 
and  can  be  seen  singly  only  through  the  aid  of  a  powerful 
microscope.  We  do  not  know  all  about  their  life  pro- 
cesses, but  we  have  learned  much  about  their  effect. 
We  constantly  hear  about  these  plants,  cither  under  their 
correct  name,  bacteria,  or  under  the  names  of  germs  <>r 
microbes.  Two  incorrect  ideas  concern- 
ing bacteria  are  prevalent,  —  one,  that 
bacteria  are  animals,  and  the  other,  that 
all  of  them  are  harmful.  It  is  definitely 
known  that  bacteria  are  plants  ;  that 
small  as  they  are,  they  are  among  the 
most  important  plants  in  the  world  ;  that 
most  of   them  are  helpful,   and  only  a  FlG 

few    harmful.     They    are,    however,    so 

much    like    the    one-celled    animals    (protozoa)    that    the 

word  germ  is  not  unnaturally  used  to  cover  both. 

242.  Shape  and  Size  of  Bacteria.  —  Bacteria,  according  to 
their  shape,  are  grouped  into  three  classes:  (1)  round 
(the  cocci);  (2)  rod-shaped,  like  an  unsharpened  pencil 
(the  bacilli);  (3)  those  that  are  shaped  like  a  corkscrew 
(the  spirilla).  Most  of  the  names  for  the  different  bacteria 
contain  one  or  another  of  these  words,  thus  indicating  the 
shape  of  the  bacterium1  under  discussion.  The  spirilla 
and  the  bacilli  often  have  on  one  or  both  ends  tiny  thread- 

1  Bacterium,  singular  of  bacteria. 
34:; 


344 


THE  SMALLEST  PLANTS   (BACTERIA) 


like  hairs  by  which  they  move,  so  that  the  first  observers 
not  unnaturally  thought  they  were  animals. 

An  indication  of  the  minuteness  of  these  plants  is  that 
fifteen  hundred  of  the  rod-shaped  bacteria  will  hardly 
reach  across  the  head  of  a  pin.  When  bacteria  are  grown 
in  the  proper  kind  of  substance,  there  are  so  many  in  a 
cluster  that  they  appear  as  tiny  spots  or  points,  often 
tino-ed  with  a  faint  color.  When  seen  alone  under  the 
microscope,  they  are  clear,  almost  transparent,  and  color- 
less, and  often  have  a  bright,  shining  spot  on  the  inside. 

243.  Where  Bacteria  are  Found. 
—  Bacteria  are  everywhere,  — 
in  the  air,  as  invisible  dust ;  in 
the  upper  layers  of  the  soil ; 
and  in  water.  We  breathe  in 
the  microbes  of  the  air  with 
every  breath,  but  generally 
with  no  injurious  result.  Every 
bacterium  has  its  own  work  to 
_  do,  and  a  healthy  body  gives 
Figure  368.  — Soil  Bacteria,      little      opportunity      for      most 

kinds  of  bacteria  to  do  harm. 

244.  Conditions  Necessary  for  the  Growth  of  Bacteria. — 
Like  all  other  plants,  bacteria  must  have  all  the  proper 
conditions  before  they  can  grow  and  multiply.  Their 
food  is  chiefly  plant  or  animal  matter,  but  they  cannot 
make  use  of  food  except  in  the  presence  of  warmth  and 
moisture,  and  most  of  them  require  oxygen  in  addition. 
They  get  the  oxygen  from  the  surrounding  air. 

245.  Life  Processes.  —  In  the  preparation  of  their  food 
bacteria  break  up  substances  or  decompose  them,  causing 
the  condition  known  as  decay.  They  use  some  of  the 
material  resulting  from  decay ;  some  they  set  free  in  the 
air ;  and  the  remainder  is  left  on  the  earth  to  be  used  by 


LIFE  PROCESSES  345 

higher  plants.      In  changing  dea<l   matter  —  plants.  Leaves, 
and  animals  —  to   a   form   which   again  becomes  a    part    of 
the  earth,  bacteria  perform  a  service  valuable  to  man. 
Reproduction  occurs  in  bacteria  through  simple  fission. 

Sometimes  bacteria,  break  entirely  apart,  while  in  other 
cases  they  remain  connected,  forming  a  chain.  Under 
favorable  conditions  each  cell  can  grow  t « >  full  size  in  half 
an  hour  and  be  ready  to  divide  again.  It  is  this  abilil 
to  multiply  rapidly  which  makes  them  of  so  great  impor- 
tance, for  a  few  hundred  bacteria,  even  of  the  harmful 
ones,  could  produce  little  effect. 

In  the  process  of  growth,  bacteria  produce  two  sub- 
stances, enzyme  (see  page  172)  and  toxin  (toxin:  Greek, 
toxicum,  poison).  Enzymes  produce  fermentation,  a  break- 
ing-up  process  of  which  man  makes  use  to  secure  certain 
flavors  and  odors,  as  well  as  to  soften  hard  materials. 
Toxins  are  usually  poisonous  to  living  organisms,  includ- 
ing the  bacteria  which  produce  them. 

Enzymes  cause  the  pleasant  flavor  of  such  articles  of 
food  as  cheese  and  butter.  The  quality  of  tobacco  depends 
largely  upon  the  kinds  of  bacteria  which  have  been  at 
work  upon  it.  Such  bacteria  are  classed  as  helpful,  as  are 
those  which  gather  nitrogen  for  the  plants  of  the  bean 
family.  Other  helpful  bacteria  are  those  which  make  it 
possible  for  man  to  use  sponges  by  ridding  them  of  t lu- 
soft,  slimy  substance  with  which  they  are  filled  when 
alive,  as  well  as  the  bacteria  which  soften  the  useless  parts 
of  the  flax  plant  so  that  the  rest  of  it  may  be  separated 
and  made  into  linen. 

When  food,  air,  warmth,  or  moisture  is  not  sufficient, 
bacteria  cease  to  grow  and  go  into  a  resting  state.  That 
is,  they  change  their  form,  and  surround  themselves  with 
a  substance  which  protects  the  soft  protoplasm  from  being 
harmed    by    freezing,    heating,    or    drying.      The    simple 


346  THE  SMALLEST  PLANTS   (BACTERIA) 

plants  all  do  this,  but  the  simpler  the  plant,  the  more 
easily  does  it  resist.  It  is  this  ability  to  withstand  un- 
favorable conditions  and  to  resume  growth  when  condi- 
tions change  for  the  better  that  makes  bacteria  such  "  good 
friends  and  such  bad  foes." 

LABORATORY  STUDY  OF  BACTERIA 

Prepare  culture  plates  of  agar-agar  from  the  following  formula : 

Agar-agar  Formula  for  1000  c.c. 

Agar-agar 1 15  grams 

Beef  extract        3  grams 

Peptone 10  grams 

Salt 5  grams 

Water 1000  grams 

Boil  material  for  the  agar-agar  formula ;  add  sodium  hydrate  till  the 
color  of  litmus  paper  is  not  changed ;  cool  to  about  56  C,  and  beat 
into  this  one  whole  egg,  including  the  shell.  Warm  slowly  to  the  boiling 
point  and  continue  till  the  egg  is  firmly  coagulated;  then  strain  the  clear 
medium  through  a  cheese-cloth  on  to  moist  cotton  in  a  filter  funnel. 

Work  rapidly.  Cool,  and  then  boil  once  more.  Filter  through  cotton 
into  test  tubes.  Each  tube  should  not  be  more  than  a  quarter  full.  Plug 
the  tubes  with  cotton.  Then  sterilize  this  mixture  in  the  test  tubes  by 
placing  them  upright  in  water  and  boiling  twenty  minutes  on  each  of 
three  successive  days.  Let  part  of  the  test  tubes  cool,  having  the 
plugged  end  elevated  half  an  inch.  These  are  called  slant  agar  tubes. 
When  petri2  cultures  are  needed,  melt  up  a  sterile  agar  tube  and  pour 
into  a  sterile  petri  dish. 

1.  To  show  that  bacteria  are  present  on  one's  hands.  Draw  the  fingers 
of  the  u.nwashed  hand  across  the  surface  of  the  agar-agar  in  petri  dish. 
Cover  and  set  away  for  four  days  at  room  temperature  or  two  days  at 
body  temperature. 

2.  To  show  that  fewer  bacteria  are  present  on  freshly  washed  hands. 
Draw  the  fingers  of  the  washed  hand  across  the  surface  of  the  agar-agar. 
Cover  and  set  away. 

3.  To  show  that  bacteria  lodge  under  the  nails.  Place  on  culture  plates 
scrapings  from  under  finger  nails,  (1)  before  washing  the  hands,  (2)  after 
washing  the  hands. 


1  Secured  at  most  drug  stores.  2  Flat,  round  dish  with  cover. 


BACTERIA   IN   RELATION    TO    MILK  347 

4.  To  show  that  heating  milk  reduces  the  number  of  active  bacteria. 

Sprinkle  drops  of  milk  and   water  on  agar-agar   pctri   dish,      1      oatu 
milk,  (2)  pasteurized,  (8)   boiled.    (I'sr  mv  tenth  milk  and  nine  tenths 
sterilized  water.) 

5.  To  show  that  bacteria  change  the  medium  in  which  they  grow. 
Besides  the  number,  form,  size,  and  color  of  the  colonies,  note  whether 
any  change  takes  place  in  the  agar-agar. 

6.  To  show  that  bacteria  grow  best  in  the  presence  of  warmth  and 
moisture,  compare  those  grown  under  such  conditions  with  th  »wn 
in  a  dry  or  a  cold  place.  Note  the  influence  |  a  |  of  warmth.  (6)  of  cold, 
on  the  rapidity  of  growth. 

7.  To  show  that  bacteria  are  in  the  air,  expose  the  surface  of  the  cul- 
ture plate  for  a  few  seconds. 

8.  To  show  that  flies  distribute  bacteria.  Let  a  My  walk  across  the 
surface  of  the  agar-agar  in  the  petri  dish. 

If  bacteria  have  an  opportunity,  they  work  od  every- 
thing which  is  capable  of  decay,  and  so  we  need  to  know 
how  to  prevent  their  working  upon  food  and  other  things 
which  we  do  not  wish  to  ''spoil."  Several  ways  in  com- 
mon use  are  :  (1)  cold  storage,  where  there  is  not  warmth 
sufficient  for  the  growth  of  bacteria:  (2)  the  use  of  salt 
and  other  chemicals  to  prevent  their  getting  a  start,  as  in 
the  curing  and  smoking  of  meat;  (o)  drying  fruit  and 
meat,  thus  removing  water,  a  necessary  condition  for 
growth;  and  (4)  heating  fruit,  vegetables,  milk,  etc.,  and 
sealing  them  in  cans  or  jars  while  hot,  thus  killing  any  bac- 
teria the  substances  may  contain  and  keeping  all  othi 
out.  Anything  prepared  in  this  way  is  preserved  by 
being  made  sterile  or  aseptic  (Greek,  sepein^  to  make 
putrid). 

246.  Bacteria  in  Relation  to  Milk.  —  (Sec  also  Part  II.) 
Milk  as  it  comes  from  the  healthy  cow  is  practically  I: 
from  bacteria  of  any  kind.  The  number  of  bacteria  present. 
however,  is  not  of  so  much  importance  as  the  kind.  But 
if  a  large  number  of  bacteria  are  allowed  to  get  into  the 
milk,  some  of  them  are  sure   to  be   harmful  and   may  find 


348 


THE  SMALLEST   PLANTS   (BACTERIA) 


conditions  so  favorable  for  their  growth  as  to  make  trouble 
for  the  person  using  the  milk. 

A  high  grade  of  milk  will  not  contain  more  than  500  to 
1000  bacteria  per  cubic  centimeter.  Such  milk  has  been 
well  cared  for  and  comes  from  healthy  cows.  Some  cities 
permit  milk  to  be  sold  that  contains  as  many  as  100,000 
and  some  even  more  bacteria  per  cubic  centimeter.  Such 
milk  comes  from  unhealthy  cows  or  dirty  barns,  or  has 
been  kept  too  long,  or  has  "changed  hands  "  too  many  times. 

To  deliver  pure  milk  to  the 
consumer  costs  the  producer 
time,  care,  and  money,  and 
consumers  should  be  willing  to 
pay  more  for  milk  which  has 
had  proper  care. 

Ice  prevents  harmful  bacteria 
from  multiplying  sufficiently 
to  make  milk  dangerous,  unless 
the  milk  is  kept  for  too  long 
a  time.  Preservatives,  soda, 
borax,  boric  acid,  formaldehyde, 
and  the  like  are  sometimes  used  to  prevent  the  growth  of 
bacteria.  In  some  cases  no  immediate  harm  seems  to 
come  to  the  persons  using  milk  thus  preserved,  but  some 
of  these  substances  are  poisonous,  and  pure  milk,  properly 
cared  for,  does  not  need  them.  So  the  use  of  any  milk 
in  which  preservatives  are  found  should  be  avoided. 

A  harmless  bacterium  gets  into  milk  kept  too  long  and 
forms  lactic  acid,  thus  giving  the  milk  a  sour  taste  and 
causing  it  to  curdle.  Sour  milk  is  perfectly  wholesome  for 
food,  but  the  taste  is  disagreeable.  In  1857  Pasteur  dis- 
covered this  bacterium.  He  also  found  that  milk  could  be 
kept  for  several  days  without  becoming  sour,  after  it  had 
been  heated  sufficiently  to  kill  this  bacterium. 


Figure  369.  —  Clean  Milk. 
Showing  oil  globules. 


Louis  Pasteur  (1822-1895)  was  a  celebrated  French  chemist 
and  biologist. 

After  filling  various  academic  positions.  Pasteur  was  appointed 
Professor  of  Chemistry  at  the  Sorbonne.  in  Paris,  in  1867 

Pasteur  is  especially  famous  for  his  researches  in  bacteria.  In 
1884  he  discovered  a  method  of  curing  or  preventing  hydrophobia 
by  inoculating  with  the  poisonous  virus  in  an  attenuated  form. 

In  1874  the  French  government  gave  Pasteur  a  pension  of 
twenty  thousand  francs,  which  they  increased  the  following  year, 
in  consideration  of  his  services  in  science  and  industry. 


SOURCES  OF   DANCER   IX    MILK 


WW) 


This  process,  called  after  its  discoverer  pasteurization, 
consists  in  heating  milk  for  twenty  minutes  al  a  tempera- 
ture of  60°  C,  or  to  a  higher  degree  for  a  Bhortei  time,  and 
then  cooling  it  rapidly.  This  procedure  kills  nearly 
all  the  bacteria  in  the  milk  and  does  not  change  the  taste 
or  make  it  hard  to  digest.  Milk  is  not  rendered  abso- 
lutely sterile,  but  it  is  a  much  safer  food,  especially  for 
infants.  At  best  pasteurization  is  only  a  corrective  or 
precautionary  measure,  and  we  should  demand  that  milk 
be  kept  clean  and  thus  free 
from  bacteria. 

Most  raw  milk  products  have 
their  own  forms  of  bacteria, 
but  most  of  these  forms  are 
helpful.  The  flavor  of  June 
butter  is  imparted  by  a  bac- 
terium different  from  the  one 
in  January  butter.  So  with 
cheese,  each  brand  or  flavor 
receives  its  taste  through  the 
action  of  a  special  bacterium. 

At  every  step  in  the  use  and  manufacture  of  milk,  it  is 
necessary  to  know  the  conditions  under  which  the  helpful 
bacteria  work  best,  and  how  to  keep  out  the  harmful  on 

247.  Sources  of  Danger  in  Milk. — The  cow  herself  may 
be  unhealthy  and  her  disease  transmitted  through  the 
milk.  Of  the  several  diseases  which  this  animal  may 
give,  tuberculosis  is  the  most  common.  Children  are 
more  liable  than  adults  to  take  the  disease  in  this  way. 
There  is  no  necessity  to  be  in  doubt  about  a  cow's  being 
infected  with  tuberculosis,  for  in  18lJ0  Koch  discovered 
the  tuberculin  test,  which  enables  the  dairyman  to  detect 
the  disease.  This  test  is  now  commonly  applied  and  in 
some  cities  owners  of  herds  which  have  been   tested   and 


Figure  370.  —  Dirty  Milk. 


350 


THE  SMALLEST   PLANTS   (BACTERIA! 


found  free  from  disease  are  allowed  to  sell  their  milk  as 
"certified,"  though  the  meaning  of  this  term  varies.  Not 
only  is  the  raw  milk  from  tubercular  cows  dangerous,  but 
also  the  butter  and  cheese  made  from  it. 

Bacteria  multiply  rapidly  and  remain  active  while  milk 
is  warm,  and  so  it  should  be  cooled  as  soon  as  possible 
after  it  has  been  taken  from  the  cow.  Milk  should  not 
be  used  when  it  is  too  old,  for  in  that  case  the  harmless 

bacteria  may  all  have  died  and 
harmful  ones  taken  their  places. 
Milk  should  not  be  left  in  a 
metal  container,  nor  open  to 
the  air,  nor  placed  in  an  ice 
chamber  where  it  can  absorb 
the  odors  of  other  foods. 

Ice  cream  should  be  eaten 
only  when  fresh,  for  poisons 
(ptomaines)  are  formed  by  the 
action  of  bacteria,  especially  in 
ice  cream  which  has  been  melted 
and  then  refrozen.  Ice  cream 
should  be  made  under  clean  and  healthful  conditions,  and 
should  never  be  exposed  to  the  air  of  the  street. 

Men  ivho  made  the  Study  of  Bacteria  Possible.  —  The 
inventor  of  the  microscope  should  be  placed  at  the  head 
of  the  list  of  men  who  made  the  study  of  bacteria  possi- 
ble, for  without  this  instrument  we  should  not  know  that 
such  plants  exist.  We  do  not  know  who  the  actual  in- 
ventor was,  but  the  microscope  was  little  more  than  a 
toy  until  it  was  improved  by  a  Dutch  naturalist,  Leeu- 
wenhoek  (Lu'wen-hook)  in  the  latter  part  of  the  seven- 
teenth century.  Next  in  the  study  of  bacteria  comes 
Pasteur,  who  discovered  and  studied  them  in  their  rela- 
tion to  the  souring  of  milk  and  in  other  fermentations. 


Figure  371. —  Beef  Jelly. 
Exposed  in  sanitary  dairy. 


HEALTHY  BODIES   AND   BACTERIA 


351 


Finally  comes  Koch,  who  discovered  a  way  of  separating 
bacteria  so   that   each  kind   may  be  studied    by   Itself,  a 
method  called   getting  a  "pur.'   culture,"  and   who   aJ 
invented  the   tuberculin  test.     Most  of   our  facts  about 

bacteria   have   been   learned    during    the    past    thirty-fi 
years. 

248.  Healthy  Bodies  and  Bacteria.  —  So  much  has  been 
said  about  harmful  bacteria  that  a  word  of  caution  is 
needed.  Two  facts  should 
make  us  take  a  sane  view  of 
the  situation :  (1)  for  every 
harmful  bacterium  there  are 
thousands  of  helpful  ones  ;  and 
(2)  harmful  ones  cannot  do 
their  work,  or  even  live,  in  a 
perfectly  healthy  body,  for  such 
a  body  is  constantly  preparing 
a  substance  (antitoxin)  which 
neutralizes  the  bacterial  poison 
(toxin).  Our  chief  aim,  then, 
should  be  to  keep  well,  and  a  few 

simple  rules  of  hygiene  will  accomplish  this.  (1)  Spend 
as  much  time  as  possible  exercising  in  the  open  air. 
(2)  Sleep  as  many  as  eight  hours  out  of  twenty-four  in 
a  well-ventilated  room  or  out  of  doors.  (3)  Bat  only 
food  which  agrees  with  you,  and  not  too  much  <d  that. 
(4)  Wear  seasonable  clothing.  (5)  Keep  the  skin  clean 
through  frequent  bathing.  (6)  Have  a  definite  occupa- 
tion, work  faithfully  at  it,  do  your  best,  and  don't  worry. 


Figure  372.  —  Beef  Jelly. 
Exposed  in  unsanitary  dairy. 


SUMMARY 

The  smallest  and  simplest  of  all  the  plants  are  the 
bacteria.  Most  of  them  are  helpful,  ridding  the  earth  of 
waste  material,  giving  flavor  to  food,  gathering  nitrogen 


352 


THE  SMALLEST   PLANTS   (BACTERIA) 


from  the  air  for  plants,  and  aiding  in  the  making  of  linen 
and  sponges.  Some  bacteria  are  harmful  and  cause  dis- 
eases in  plants  and  animals.  Bacteria  are  spherical, 
spiral,  or  rod-shaped.  They  are  found  everywhere,  un- 
less special  pains  have  been  taken  to  remove  them.  If 
they  have  plenty  of  food,  air,  moisture,  and  warmth,  they 

multiply  rapidly,  and 
they  go  into  the  resting 
state,  in  which  they  can 
remain  for  a  long  time 
if  any  or  all  of  the 
necessary  conditions  of 
growth  are  lacking. 
The  harmful  bacteria 
by  their  growth  secrete 
a  poisonous  substance. 
When  there  are  enough 
bacteria  present  to  make 
a  large  quantity  of  toxin, 
the  animal  or  plant  host 
is  made  ill.  Some  bac- 
teria, especially  in  the 
resting  state,  can  bear 
freezing  or  boiling  with- 
out being  killed.  In  order  to  make  anything  "  keep,"  it 
is  necessary  either  to  kill  all  the  bacteria  by  making  the 
substance  sterile  or  aseptic,  or  we  must  put  into  it  a 
preservative  in  which  the  bacteria  cannot  grow.  We 
should  exercise  great  care  to  avoid  the  bacteria  known  to 
produce  disease. 

Milk,  one  of  the  most  important  articles  of  food,  is  a 
possible  source  of  danger  from  harmful  bacteria  which  may 
get  into  it  in  various  ways.  Milk  should  be  kept  cold, 
and  should  be  used  before  it  is  too  old.     The  harmless 


Figure  373. —  Bad  and  Good  Bottling. 

The  metal  cap  keeps  out  dirt  which 
can  get  by  the  paper  stopper. 


SUMMARY  353 

bacteria  in  milk  form  lactic  acid  and  cans.-  the  milk  to  BOlir. 
Tlie  growth  of  these  bacteria  can  be  checked  bv  pasteuriz- 
ing the  milk.     Ice  cream,  if  too  old,  is  dangerous,  for  the 

slow-growing  bacteria  have  had  a  chance  t<»  develop. 

The  men  who  did  the  most  to  make  the  study  of  bacteria 
possible  were  Leeuwenhoek,  who  improved  the  microscoj 

Pasteur,  who  discovered  bacteria  in  milk,  and  Koch,  who 
found  the  way  to  make  a  pure  culture  and  to  tesl  cows  for 
tuberculosis.  Many  students  are  devoting  their  lives  to 
finding  out  about  the  various  bacteria. 

K very  one  should  know  the  main  facts  about  bacteria  30 
that  he  may  not  have  a  foolish  fear  of  them,  but  may  be 
able  to  take  reasonable  precautions  against  the  harmful 
kinds.  Since  a  healthy  body  is  the  best  safeguard  against 
harmful  bacteria,  we  should,  observe  the  laws  of  hygiene  in 
order  to  keep  well,  and  at  the  same  time,  avoid,  when 
possible,  the  bacteria  which  produce  disease. 

QUESTIONS 

What  are  the  main  points  of  likeness  between  a  bacterium  and  a  bean 
plant?  What  has  the  pleurococeus  which  the  bacterium  lacks?  Bow 
can  food  be  protected  from  harmful  bacteria?  In  what  respects  are 
bacteria  harmful  to  milk?  In  what  respects  helpful?  Why  are  a  : 
harmful  bacteria  not  injurious  in  a  healthy  body  ?  If  one  bacterium 
divides  every  half  hour,  and  all  live,  how  many  will  there  be  at  the  end  of 
twenty-four  hours  ?  (Solve  by  arithmetic  or  by  algebra.l  Why  <1»  B  an 
apple  with  a  broken  skin  decay  more  rapidly  than  one  in  which  the  akin 
is  not  broken  ?     Why  should  one  not  put  ice  into  water  to  cool  it  '.' 

REFERENCES 

Conn,  The  Story  of  Germ  Life. 
Frankland,  Our  Secret  Friends  and  Foes. 
Prudden,  The  Story  of  the  Bacteria. 
Radot,  The  Life  of  Pasteur. 
Woodhead,  Bacteria  and  Their  Products, 

U.  S.  Bulletin  No.  56,  Hygienic  Laboratory  Bulletin.     Milk  and   Its 
Relation  to  Public  Health. 


CHAPTER   XXIV 

PUNGI 

249.  Fungi. — The  Fungi  are  of  importance  to  us  be- 
cause: (1)  some  can  be  used  as  food  (the  so-called  mush- 
rooms); (2)  one  of  them,  the  yeast  plant,  is  used  in 
making  bread,  beer,  and  wine  ;  (3)  others  spoil  our  food 
when  they  grow  on  bread  and  cake;  (4)  they  cause  many 
diseases  in  plants. 

Fungi  differ  from  the  higher  plants  in  two  respects. 
They  are  colorless,  or  nearly  so,  chiefly  because  they  have 
no  chlorophyll.  They  are  dependent  for  food  on  plant  or 
animal  substances,  either  dead  or  alive,  because  they  lack 
chlorophyll  and  hence  cannot  make  their  own  foods  as  the 
green  plants  do. 

Fungi  which  live  on  the  substances  or  juices  of  live 
plants  or  of  animals  are  called  parasites  (Greek,  para,  be- 
side ;  sitos,  food)  ;  and  those  that  live  on  dead  objects 
are  called  saprophytes  (Greek,  sapros,  rotten;  phyton, 
plant). 

250.  The  Yeast  Plant.  —  This  plant  is  a  unicellular  fungus, 
too  small  to  be  seen  by  the  naked  eye.  It  is  oval  or  almost 
round  in  shape,  and  is  nearly  colorless.  It  has  all  the 
parts  of  a  typical  cell,  although  the  nucleus  cannot  be  seen 
without  a  special  stain.  Because  it  lives  upon  dead  vege- 
table matter,  it  is  a  saprophyte. 

The  Work  of  the  Yeast  Plant.  —  In  the  making  of 
bread,  we  know  that:  (1)  yeast  secretes  an  enzyme  which 
breaks  up  sugar  into  simpler  substances;   (2)  in  this  pro- 

354 


THE    YEAST   PLANT 


:;:>:> 


Figure  374. —  Yeast. 


cess  alcohol   is  formed  and  carbon   dioxide    is  sel   five; 

(3)  the  yeast  lives  on  the  proteid  substances  in  the  flour; 

(4)  both  the  gas  which  makes  bread  Light  and  the  alcohol 
are    driven    off    by    the 
heat  of   the  oven  when 
the  bread  is  baked. 

Use    is    made    of   the 
enzymes    and    yeast    in 
the  making  of  beer,  ah  , 
and    porter.      The    pro- 
cess of  the  manufacture 
of  these  products  is  as  follows:    The  grain,  usually  barley, 
is  soaked  in  water  to  soften  it.      The  grain  is  kept   warm 
and  moist  until  it  sprouts,  and  in  this  condition  is  called 
malt.     It  is  then  heated  and  crushed.      Fermentation  tal. 
place  when  warmth  and  moisture  are  supplied,  the  enzyme 

diastase  breaking  up 
the  starch  into  sugars. 
The  liquid  or  wort  from 
this  process  is  boiled 
with    hops.       The    wort 

is  again  fermented,  this 
time  by  tin-  aid  of  yeast, 
the  action  of  which  is 
to  break  up  the  sugars 
into  carbon  dioxide  and 
alcohol.  Yeast  of  only 
one  kind  is  used  (a  pure 
culture)  and  care  is 
taken  to  keep  the  tem- 
perature favorable  to  its  most  rapid  growth.  As  the  yeasl 
grows  and  breaks  up  t lie  sugar,  it  forms  quantities  of  gas 
and  alcohol.  In  bread  these  are  temporary  by-products 
which  are  lost  in  the  baking,  but   in   the   manufacture  of 


Figure  375.  —  Fermentation  Tubes. 


356  FUNGI 

beer  they  are  the  product  sought,  and  every  means  is 
taken  to  retain  them. 

Before  the  action  of  bacteria  and  yeast  were  understood, 
much  trouble  was  experienced  in  getting  uniform  products, 
owing  to  the  presence  of  undesirable  bacteria  and  yeasts. 
The  possibility  of  making  pure  cultures,  the  use  of  the 
microscope,  as  well  as  the  tests  which  are  made  in  the 
laboratories  at  every  step  of  the  manufacture,  have  placed 
the  industries  of  bread-making  and  brewing  on  a  scientific 
basis. 

251.  Reproduction  of  the  Yeast  Plant. — The  method  of 
reproduction  of  the  yeast  plant  is  similar  to  that  of  the 
bacterium,  but  differs  from  it  in  that  instead  of  dividing: 
exactly  in  two,  a  bud  usually  pushes  out  from  the  side  of 
the  mature  plant.  Sometimes  the  second  plant  will  form 
a  bud  before  it  breaks  awa}^  from  the  first,  and  so  a  chain 
is  made.  Oftentimes  a  single  plant  puts  forth  more  than 
one  bud  (Figure  374). 

LABORATORY    STUDY 

Prepare  a  Pasteur  solution,  a  good  food  for  yeast,  as  follows : 

Potassium  phosphate 10  parts 

Calcium  phosphate 1  part 

Magnesium  sulphate 50  parts 

Ammonium  tartrate 50  parts 

Cane  sugar 750  parts 

Sufficient  water  to  make  a  total  of  5000  parts.  (This  may  be  used  for 
the  culture  of  other  molds  than  yeast  and  also  for  bacteria.) 

Yeast.  —  Examine  yeast  cells  under  low  power.  Note  their  glistening 
appearance  and  their  number.  Under  the  high  power  try  to  find  all  parts 
of  a  typical  cell.  Label  and  draw.  Look  for  budding  cells  and  chains 
of  cells.  Draw.  Make  a  thick  paste  of  water,  yeast,  and  flour.  Put  an 
equal  amount  into  each  of  three  tumblers.  Place  one  tumbler  in  a  cool 
place.  Into  one  of  the  remaining  stir  a  teaspoonful  of  sugar  and  set  both 
tumblers  in  a  warm  place.  Examine  several  times  a  day  and  write  down 
all  the  differences  you  observe  in  the  three  mixtures.  Try  to  give  a  reason 
for  everything  you  observe. 


BREAD    MOLD 


357 


252.    Bread  Mold.  —  When  examined  with  the  naked  eye, 

bread  mold  appears  like  a  thick   mass  of  felt,  made  up 


Figure  376.  —  Bread  Mold. 

of  colorless,  closely  interwoven  threads.  These  threads 
are  called  hyphce  (hi'fe:  Greek,  hyphe,  web)  and  are  of 
two  kinds,  one  lying  on  the  surface  of  the  bread  or  just 

below  it,  and  the  other  standing 
upright  above  the  surface.  The 
first   are  the   nutritive    hyphaB,  and 


Figure  377.  -    Mold 
Grown  from  Water. 


Figure  378.  —  Cap   Fungi. 


the  second  the  reproductive.     On  the  ends  of  tin-  latter 
are  round  black   bodies  which  are   full   of  Bpores,  each  of 


358 


FUNGI 


which  is  capable  of  producing  a  new  mold  plant,  if  it  falls 
into  a  place  where  conditions  are  favorable  for  growth,  — 

that  is,  where  it  has 
plenty  of  food,  the  right 
degree  of  warmth,  and 
sufficient  moisture. 
Other  kinds  of  fungi 
may  usually  be  found 
on  a  loaf  of  bread  after 
a  day  or  two,  as  spores 
of  many  kinds  of  molds 
are  floating  in  the  air  at 
all  times  (Figure  376). 
253.  Other  Fungi. — A  common  fungus  is  the  one  that 
kills  flies  in  the  fall.  At  that  time  a  dead  fly  is  often  ob- 
served on  a  window  or  mirror,  the  body  surrounded  by 
a  whitish  ring.  Such  a  fly  has  been  killed  by  fungus 
hyphre  which  have  filled  the  body.     The  ring  is  composed 


Figure  379.  —  Puffballs. 


Figure  380.  —  Puffballs. 


of  spores  thrown  off  from  the  ends  of  the  hyphse  which 
have  burst  through  thin  places  between  the  segments  of 
the  fly's  body. 


OTHER   FUNdl 


359 


Figure  381.  — Bracket  Fungus. 
The  fruiting  body  of  the  fungus. 


Figure  383.  —  Pear  Scab. 


Figure  382.  —  Tree  Killed  by  Bracket       Figure  384.      Si  tion  through 
Fungus.  the  Scab. 


360 


FUNGI 


-  I      •.*•;  \Wd  - 


• 


Other  common  fungi  are  potato  blight,  red  rust  of  wheat, 
corn  smut,  which  produces  the  black  mass  found  in  an 
ear  of  corn,  and  the  bracket  fungi,  which  grow  in  large 

numbers  on  the  trunks  of  trees 
and  whose  hyphae  cause  the 
death  of  the  tree  (Figures  381 
and  382). 

The  fungi  used  for  food 
are  nourishing,  but  there  is  a 
prejudice  against  their  use  be- 
cause other  fungi  which  re- 
semble them  closely  are  poison- 
ous. As  a  matter  of  fact,  it  is 
an  easy  task  to  learn  to  dis- 
tinguish the  edible  from  the 
poisonous  fungi.  While  the  harmless  fungi  are  now  used 
as  food  much  more  than  formerly,  only  a  few  varieties  are 
raised  for  trade  purposes  (Figures  378-380). 


aX£3 


Figure  385.  —  Spores. 

Section  through  a  leaf 
injured  by  fungus. 


LABORATORY    STUDY 

Wet  a  piece  of  bread,  put  a  tumbler  over  it,  and  set  it  in  a  warm  place 
for  three  or  four  days.  Examine  without  the  microscope  to  get  the 
general  appearance.  With  the  microscope  note  (1)  the  clear,  colorless 
threads  (hyphae)  making  up  the  mass  ;  (2)  the  groups  of  spore-bearing 
bodies,  black  and  round,  on  the  ends  of  the  upright  stalks;  (3)  the  spores 
coming  out  of  them. 

254.  Lichens.  —  Lichens  (H'kens)  are  grayish  green 
plants  which  look  like  scales.  They  grow  on  old  fences, 
rocks,  trees,  and  the  like  and  are  especially  noticeable 
after  a  rain.  A  lichen  is  made  up  of  the  hyphse  of  a 
fungus,  which  inclose  the  cells  of  an  alga.  The  algal 
cells  in  a  flat  lichen  are  usually  near  the  top  and  bottom, 
and  the  fungus  is  in  the  middle  of  the  plant.  The  alga 
uses  the  moisture  which  the  fungus  collects  and  brings  to 
the  plant,  and,  by  the  use  of  its  chlorophyll,  makes  food,  a 


LICHENS 


361 


part  of  which  is  used   by 

the  fungus.     The  Latter, 

after  it   has  become   ac- 
customed   to    the    alga, 

cannot    live   apart    from 

it,   and    the    alga,   while 

it    can    live     by    itself, 

appears  plump  and  pros- 
perous when  it  is  found 

surrounded     by     fungal 

threads.       The    partner- 
ship, therefore,  seems  to 

be  helpful  to  both  plants. 

Such  a  relation  between 

organisms    is    known  as 

symbiosis      (sim-bi-6'sis: 

life      together  ;      Greek, 

syn,    with  ;     bios,    life). 

(Figures  386  and  387.) 

Lichens   are    interesting    chiefly    as    representing    this 

peculiar  interdependence  of  plants.      They  have  lit  tit-  or 

no  economic  importance,  although  in  the 
Arctic  Regions  they  furnish  a  supply 
of  food  for  the  reindeer. 

We  close  the  study  of  the  simplest 
plants  with  the  fungi.  As  in  the  ca 
of  the  bacteria,  men  have  Bpenl  their 
lives  studying  the  fungi,  especially 
those  which  cause  disease.  Much  lias 
been  accomplished,  but  a  great  deal 
remains  to  be  done  in  finding  out  the 
cure  for  certain  fungus  diseases,  espe- 
cially those  that  attack  vegetables  which 

tion  of  Lichen.  W6  use  for  food. 


Figure  386.  —  Lichens. 


362 


FUNGI 


FIELD  TRIP  FOR   THE  STUDY  OF  LICHENS 

After  a  rainy  period,  examine  trees,  rocks,  old  fences,  posts,  and  sim- 
ilar places  for  lichens.  Note  the  form,  color,  and  kinds  of  trees  having 
the  greatest  number  of  lichens  ;  the  trees  having  the  smallest  number,  and 
the  side  of  the  tree  having  the  greatest  number.  Make  the  same  exam- 
ination during  a  dry  period. 


SUMMARY 

Fungi  are  plants  similar  in  structure  to  the  algae,  but 
they  lack  chlorophyll.  On  this  account  fungi  cannot 
make  their  own  food,  but  always  have  to  use  that  pre- 
pared by  another  organism.  As 
they  lack  chlorophyll,  fungi 
cannot  use  carbon  dioxide,  and 
as  a  result  that  which  they 
produce  by  respiration  is  cast 
off  into  the  air,  as  is  the  case 
with  animals  and  with  green 
plants  placed  in  the  dark. 

The  fungi  which  are  most 
important  economically  are  the 
yeasts  used  in  making  bread, 
or  beer  and  other  fermented 
liquors ;  the  edible  mushrooms  ; 
those  that  spoil  food,  as  bread  mold,  and  those  which 
cause  plant  diseases,  such  as  corn  smut  and  wheat  rust. 
Fungi  reproduce  by  means  of  spores.  The  mutually  help- 
ful relation  in  which  fungi  and  algse  live  in  the  lichen  is 
called  symbiosis.  Animals  which  show  the  same  relation 
are  of  little  economic  importance  in  this  country. 


Fiqure  388. — Spores  of  Corn 
Smut. 

A  farm  fungus. 


QUESTIONS 

What  is  the  color  of  fungi  ?  Are  they  ever  green  ?  Why  not  ?  How 
does  their  food  differ  from  that  of  green  plants  ?  How  does  the  yeast 
plant  produce  changes  in  flour  ?     In  malt  ?     How  does  the  work  of  bread 


REFERENCES  363 

mold  and  yeast  compare  with  that  of  tin-  bean  '.'     What  are  lichens  '.'     Do 
lichens  grow  equally  well  on  all  Bides  of  a  tree  '.'      On  all  fcn  i  How 

do  they  appear  when  wet?     When  dry  '.'     What  colon  do  you  find  among 

them  ? 

REFERENCES 

Atkinson,  Mushrooms. 

Bennett  and  Murray,  Cryptogamic  Botany. 

Cook  and  Berkley,  Fungi. 

Gibson,  Our  Edible  Toadstools  and  Mushrooms. 
Marshall  (The  Nature  Library).  Mushrooms. 
Trouessart,  Microbes,  Ferments,  and  Mold-. 
Atkinson,  High  School  Botany. 


CHAPTER   XXV 


MOSSES   AND   THEIE   ALLIES 

255.  General  Features.  —  The  plants  in  this  group  have 
more  parts,  stems,  leaves,  etc.,  than  the  fungi  and  algse 
have  ;  the  chlorophyll  is  evenly  distributed,  and  they  tend 
to  grow  erect.  The  life  history  of  the  mosses  is  more 
complex  than  that  of  the  simple  algae  (Figure  390). 

If  a  cushion  of  moss  is  examined,  it  is  found  to  be  made 
up  of  small  plants  packed  closely  together.     At  certain 

times  of  the  year  some 
of  these  plants  have  a 
stiff,  wiry,  brownish 
stalk,  surmounted  by  a 
boxlike  capsule,  on  top 
of  which  may  be  a  shaggy 
cap  or  cover  (Figures 
389  and  390). 

256.  Habitat.  —  Mosses 
grow  in  moist  places,  for 
their  rootlike  rhizoids  are  not  sufficiently  developed  to 
gather  water  from  the  soil.  They  thrive  best  in  shady 
woods,  on  decaying  logs,  and  on  stones  wet  by  spray. 
Another  reason  for  their  need  of  moisture  will  appear  in 
the  study  of  their  reproduction. 

257.  Life  History.  —  If  a  dry  moss  capsule  is  shaken, 
powdery  spores,  much  like  the  "  smoke  "  from  a  puffball, 
float  off  in  the  air.  When  these  spores  fall  on  moist 
ground,   each  sends  out  a  mass  of  very    small,   alga-like 

364 


Figure  389.  —  Types  of  Mosses. 


LIFE    HISTORY 


365 


threads  which  are  called  the  pr<>t>>/i,  ma  (pro-td-ne'mA: 
Greek,  protos,  first  ;  nema,  thread).  These  threads  pro- 
duce buds  from  which 
leafy  moss  plants  grow. 
The  latter  produce 
gametes  (reproductive 
cells  which  reproduce 
sexually)  and  so  the 
moss  plants  are  called 
gametophytes  (gamete 
plants). 

These  gametes  are  of 
two  kinds,  eggs  (large 
non-motile  cells)  and 
sperms  (motile  cells).  The  egg  cells  are  produced  in  spe- 
cial vase-shaped  organs  called  archegonia  (ar-ke-go'ni-a), 
and  the    sperm   cells   in  other   organs  called   antheridia. 


Figure  390.  —  Diagram. 
Life  history  of  moss. 


rhiroids 


Figure  391. 
Antheridial  Plant. 


Figure  392. 
Archegonial  Plant. 


When  moss  plants  arc  reproducing,  both  of  the  reproduc- 
tive organs  are  found  surrounded   by  Bterile  hairs  at    the 


366  MOSSES 

top  of  the  stems.  Some  mosses  have  both  antheridia  and 
archegonia  on  the  same  plant,  while  other  mosses  have 
only  one  kind  on  each  plant.  The  moss  plant  which 
bears  the  antheridia  is  usually  short  and  has  on  the  top 
a  rosette  of  leaves,  in  the  center  of  which  is  the  sex 
organ. 

Many  sperms  come  from  each  of  the  antheridia,  which 
move  by  the  use  of  cilia  when  water  is  present,  a  film  of 
dew  being  sufficient.  The  female  moss  plant  has  on  its 
upper  end  one  or  more  archegonia,  each  of  which  contains 
an  egg  cell.  When  the  egg  is  ripe  or  ready  to  be  ferti- 
lized, sperms  may  swim  to  it  if  water  is  present.  A 
sperm  enters  the  archegonium  and  fuses  with  the  egg  cell, 
thus  forming  a  sexual  cell,  known  as  the  fertilized  egg 
cell. 

From  this  fertilized  egg  cell  a  sporophyte  (spore  plant) 
grows  out  of  the  archegonium.  The  sporophyte  consists 
of  a  foot,  a  pad  by  which  it  gets  its  food  from  the  gameto- 
phyte,  the  seta,  a  slender  stalk,  and  the  capsule  or  spore- 
case.  While  every  mature  gametophyte  leads  an  inde- 
pendent existence,  the  sporophyte  is  a  parasite. 

Thus  in  its  life  history  the  moss  plant  has  two  distinct 
generations,  the  gametophyte  or  sexual  and  the  sporophyte 
which  reproduces  asexually  (Figure  390). 

258.  Economic  Value.  —  Mosses  have  little  economic 
value,  except  in  cold  regions  where  some  kinds  are  dug 
from  under  the  snow  for  food  for  the  reindeer.  They  are 
interesting  as  showing  a  stage  of  development  of  the 
higher  plants. 

LABORATORY   STUDY 

Moss  (Polytrichum).  Study  moss  plants  and  note  the  difference  in 
size  between  the  male  and  female  plants.  Make  a  drawing  to  show  the 
difference  in  size  and  in  the  arrangement  of  the  leaves.  Select  a  female 
gametophyte  which  has  a  sporophyte.     Draw  and  label  the  seta  or  stalk, 


MARCHANTIA 


367 


and  the  capsule,  the  box  at  the  top.     Look  for  moss  plant-  oil  trees,  &l 
the  edges  of  sidewalks,  and  on  damp  soil.     With  tin-  microscope  examine 
archegonia  and  antheridia.     When  antheridia  from   fresh  material 
used,  the  sperms  can  usually  lit-  seen  escaping  from  tin-  antheridiom. 

259.    Marchantia.  —  Marchantia  is  u  plant  belonging  t<> 

I  Do 

the  moss  group,  which  grows  in  vciv  moist  places.      It  has 
a   thin,   broad    body   or 


> 


*  "-.-  «3gn 


• 


>    «, 


thallus  (thal'ltis:  Greek, 
thallos,  a  young  shoot), 
which  is  green  on  the 
upper  surface  and  brown 
or  gray  on  the  under 
side.  In  the  middle  of 
the  thallus  is  a  midrib. 
On  the  upper  surface  are 
diamond-shaped  mark- 
ings, each  of  which  lias 
an  opening  which  leads 
to  an  air  chamber  below. 
On  the  under  side  are 
rhizoids,  which  hold  the 
plant  loosely  to  the  soil. 
The  marchantias  are 
adapting  themselves  to  a  life  on  land,  but  they  are  Btill 
dependent  upon  water.  Their  reproductive  habits  art- 
like  those  of  the  mosses  (Figures  391  and  o\^2  ). 


Figure  393.  —  Marchantia. 


LABORATORY  STUDY  OF  MARCHANTIA 

Examine  pieces  of  the  plant  and  identify  tin-  thallus.  midrib,  rhizoids, 
and  markings.  Examine  the  umbrella-shaped,  aprighl  branches  which 
bear  the  antheridia  or  male  reproductive  organs,  the  branches  with  slen- 
der projections  which  bear  the  archegonis  or  female  reprodnctivi         ma 

With  a  microscope  examine  a  cross  BOCtiOD  <»f  the  thallus,  and  ol  the 

openings  and  air  chambers. 


368  MOSSES 


SUMMARY 


Mosses  are  much  more  complex  than  algae  and  fungi. 
Specialization  is  shown  in  the  cells  which  gather  and  con- 
duct water,  the  beginning  of  the  absorptive  and  conductive 
systems  of  plants.  There  is  also  the  beginning  of  a  sys- 
tem of  getting  oxygen.  The  life  history  of  a  moss  repre- 
sents the  alternation  of  generations,  a  generation  which 
reproduces  by  spore  (asexually),  and  one  which  repro- 
duces by  egg  and  sperm  (sexually).  The  generation 
which  bears  spores  is  the  sporophyte,  and  that  which  bears 
eggs  and  sperms,  the  gametophyte. 

QUESTIONS 

In  what  respects  are  mosses  more  highly  developed  than  algse,  fungi, 
and  lichens  ?  Why  do  mosses  require  so  much  moisture  ?  Give  the  life 
history  of  a  moss. 

REFERENCES 

Leavitt,  Outlines  of  Botany. 


CHAPTER    XXVI 


FERNS  AND  THEIR  ALLIES 

260.  The  Group.  —  The  ferns  are  the  best  known  mem- 
bers of  this  group,  but  club-mosses  and  rushes  (horsetail  | 
also  belong  to  the   fern 

family.  The  study  of 
coal  mines  has  shown  us 
that  ferns  are  very  old 
plants  and  that  they 
were  formerly  much 
more  numerous  than  at 
the  present  time.  The 
plants  of  this  group 
have  real  stems,  roots, 
and  leaves,  and  most  of 
them  are  larger  than  the 
mosses.  While  the  ferns 
are  not  so  dependent 
upon  water  as  the  mosses, 
they  grow  best  in  cool, 
moist  woods  and  in  rich 
soil. 

261.  A  Typical  Fern. — 
The  fern  named  pteris 
(Figure  394)  is  the  best 
known  and  most  widely 

distributed.     The  stem  proper  is  underground  and   lives 
on  from  year  to  year,  while  the  part  above  earth  renews 

869 


Figure  394.       Pteris. 


370 


FERNS 


itself  annually.     Some  of  these  stems  reach  a  length  of 
ten  or  fifteen  feet.     They  branch  out  and  give  off  many 

fine  roots.  Leaves,  termed 
fronds,  form  from  the  upper 
surface  of  the  stem  and  grow 
up  through  the  soil  into  the  air. 
The  stem  of  the  pteris  fern  is 
composed  of  well-defined  clusters 
of  cells  which  are  grouped  into 
tissues.  These  tissues  are : 
(1)  the  epidermal  on  the  outside,  which  protect  the 
stem ;  (2)  the  fundamental,  which  make  up  the  body 
of  the  stem  and  carry  on  most  of  the  vital  processes; 
(3)  the  mechanical  tissues,  variously  grouped,  which  by 
means  of  their  thick- walled  cells  give  the  stem  firmness ; 


Figure  395.  —  Pteris  Stem. 


Figure  396.  —  Fern  Frond 
Showing  Sori. 


Figure  397.  —  Sori  Enlarged. 


and  (4)  the  conducting  tissue,  which  is  made  up  of  several 
different  kinds  of  cells,  all  of  which  carry  liquids  (Figure 
395).     The  conducting  ti«sue  extends  into  the  leaves  and 


LIFE   II I  STORY   OF    THE   FERN 


371 


Figure  398.  —  Forked  Veins  of  Fern. 


is  the  vein  of  the  leaf.  During  certain  seasons  of  the 
year,  lines  form  along  the  margin  of  the  under  surfa 
of  the  leaves.  These  lines  are  made  up  of  many  minute 
reproductive  bodies,  the 
sporangia  ( sj  >6r-an'jl-a : 
Greek,  spore,  seed;  <m- 
geion,  vessel).  Each 
sporangium  contains 
numerous  spores.  In 
some  ferns  the  sporangia 
occur  in  dots,  the  sort 
(singular,  sorus;  Greek, 
^oros,  heap).  See  Figures 
396  and  397. 
'  262.  Life  History  of 
the  Fern.  —  The  fern 
plant  just  described 
forms  spores  in  the  sporangia.  These  spores  tall  to  the 
ground  and  soon  begin  to  grow.  The  sprout  from  t la- 
spore  is  in  the  form  of  a  single  thread  and  is  a  protonema. 
From  the  fern  protonema  there  develops  a  small,  flat, 
heart-shaped  body  called  the  proihallium  (Greek,  pro, 
before;  thallos,  twig)  which  is  indispensable  to  the  life 
of  the   fern.      On  the   under  surface  of   the   ji    thallium 

grow  small  bodies,  the  antheridia 
and  archegonia.  The  ant  heridia 
produce  numerous  motile  sperm 
cells,  and  each  archegoniura  a 
single  ess  cell.  A  sperm  cell, 
.hi  finding  an  archegoniura, 
enters,  fuses  with  the  egg  cell, 
and  forms  the  fertilized  egg  cell.  The  prothallium  La  the 
fern  gametophyte.     See  section  257. 

When  an  egg  cell  is  fertilized,  it    begins   to  gr«>\\  and   a 


Figure  399.  —  Sporangia. 


372 


FERNS 


new  fern  plant  is  soon  formed.     The  young  plant  remains 
attached  to  the  prothallium  and  gains  nourishment  from 


Figure  400.  —  a,  Position  of  Sori  ;    b,  Section  of  Sorus. 

4 

it.  As  soon  as  the  young  fern  is  able  to  get  nourishment 
by  its  own  roots,  it  begins  life  as  an  independent  plant 
and  the  prothallium  dies.  There  is  the  same  alternation 
of  generations  in  the  fern  that  occurs  in  the  mosses,  the 


5pores 


Prothallium 


■Protonema 


New  Fern 


Figure  401.  —  Life  History  of  Fern. 

prothallium  being  the  gametophyte  and  the  "fern'1  the 
sporophyte,  but  the  latter  is  the  longer  lived  and  much 
the  larger  plant  (Figure  401). 


RELATED    FORMS 


373 


FIELD  TRIP  T(  I  GREENH<  >i  BE  OF   w«  K)D8  TO  8T1  DY 

FERNS 

Note  the  color  of  the  plants,  the  characteristic  fern  leaf  with  it .-,  >t  ii><» 
or  central  stalk,  its  pinnsB  or  leaflets,  and  also  the  method  of  unrolling 
from  the  base  to  the  tip.  Note  the  fruiting  dots  (sori  |  on  the  l  «:i«k  of  tin- 
leaves.  In  what  kind  of  soil  are  ferns  found?  l>"  they  gro^  best  In  the 
sun  or  in  the  shade?  l><>  the  leaves  remain  green  during  the  winu 
Note  the  underground  stem  and  its  rums.  Look  for  bads  and  young 
leaves.     Note  the  forked  veins. 


LABORATORY    STUDY 

Examine  the  cross  section  of  a  stem  and  note  the  different  kind 
tissue.     Draw  and  label:  (1)  epidermal  tissue  on  the  outside;      2     me- 
chanical, dark  brown  tissue  in  masses  near  the  center;     '■'>)  conductive 
tissue,     large     Openings ;     (4)    fundamental 
tissue  filling  the  rest  of  the  space.     With  a 
microscope   examine    the    epidermis    on   the 
under  side  of  the  leaf,  noting  the  shape  of 
the  cells  and  the  stomata.     Pull  off  a  bit  of 
the   epidermis   and    try   to    distinguish    the 
green   guard    cells.     Examine   a  sorus  with 
low    power     of     the 
microscope    and    see 
how  it  is  made  up  of 
sporangia  on  stalks. 

263.  Related 
Forms.  —  Clul> 
mosses,  horse- 
tails, and  selag- 
inella  (se-laj-in- 
el/la)  are  plants 
which  belong  to 

the  fern  group.  Clul>  mosses  bear  their  spores  in  a  spike 
on  scales  which  are  modified  leaves.  In  appearance  these 
plants  are  more  like  mosses  than  ferns  <  Figures  102  and 
403). 

Horsetail,  or  equisetum,  -rows  in  waste  or  'lamp  pla< 


Figure  402. 

b,  Sporangium  ; 

c,  Spores. 


Figure  403.  —  a.  Club 
Moss. 


374 


FERNS 


sporangial,.. 
cone" 


internode  •- 


furrows 


collar  of... 
teeth 


node- 


It  is  a  hollow  stem,  with 
joints,  a  mineral  coating  on 
the  outside  of  the  stem,  and 
the  branches  in  a  circle 
around  each  joint.  The  con- 
ductive tissue  in  this  plant 
is  arranged  near  the  surface 
of  the  stem  (Figure  404). 

Selaginella  is  seldom  seen 
in  northern  latitudes,  ex- 
cept in  greenhouses  (Figure 
405). 

264.  Economic  Importance. 
—  The  fern  group,  like  the 
mosses,  have  little  economic 
importance.  The  spores  of 
the  club  mosses  are  used  in 
making  certain  kinds  of  fire- 
works (especially  those  used 
indoors) ;  also  in  drug  stores 
to  keep  pills  from  sticking 
together.  The  plant  itself  is  used  in  Christmas  decora- 
tion. Horsetail,  so  named  from  its  appearance,  was 
formerly  cut,  tied  in  bundles,  and  used  for  scouring, 
and  this  accounts  for  its  other  name,  the  "scouring  rush." 

265.  The  Formation  of  Coal. 
—  Ages  ago  ferns  were  more 
numerous  than  they  are  now 
and  many  of  them  grew  to 
be  as  large  as  our  present 
trees.  Geologists  tell  us 
that  the  climate  was  warmer 
and  more  moist  than  it  is 
now,  and  conditions  especially  Figure  405.  — Selaginella. 


Figure  404.  —  Horsetail. 


SUMMARY  375 

favored  the  growth  of   fern  plants.      Where  these   large 

ferns  died  and  fell  to  the  ground,  great  masses  accumulated. 

As  the  earth's  surface  changed,   these  masses  became 

covered  with  soil  or  water,  and  under  tin-  influence  "i' 
heat  and  pressure  they  changed  into  coal.  At  tin-  Bame 
time  natural  <_ras  and  petroleum,  or  rock  oil,  were  formed. 
No  coal  is  being  formed  at  the  present  time,  and  when  our 

present  supply  is  exhausted,  we  shall  have  t<>  find  other 
sources  of  heat  and  power. 

SUMMARY 

Ferns  and  their  allies  are  less  dependent  on  water  than 
are  the  alg;e,  fungi,  and  mosses.  They  are  more  highly 
organized,  as  they  have  epidermis,  stomata,  mechanical 
tissue,  conductive  tissue,  stem,  roots,  and  Leaves.  Their 
life  history  shows  the  alternation  of  generations,  consisting 
of  spore,  protonema,  prothallium,  and  sporophyte.  Club 
mosses,  horsetail,  and  selaginella  are  closely  related  forms. 
Coal  was  formed  when  ferns  grew  to  the  size  of  trees  in 
regions  which  were  then  hot  and  moist. 

QUESTIONS 

What  parts  of  the  flowering  plant  are  found  in  the  fern  '.'  In  an  animal 
what  corresponds  to  epidermal  tissue?  to  conductive  tissue ?  to  funda- 
mental tissue?  to  mechanical  tissue?  Compare  the  life  history  of  a 
moss  and  a  fern.     Why  can  ferns  do  with  less  water  than  mose  Illus- 

trate by  diagrams  or  sketches  the  life  history  <>t"  a  fern.      What  plants 
related  to  ferns  ?    Tell  how  coal  beds  were  formed. 

REFERENCES 

Bergen,  Foundations  of  Botany.  Bryophytes,  page  277,  Pteridophj 
page  286. 

Campbell,  A  University  Textbook  of  Botany,   Bryophytes,  pa 
Pteridophytes,  page  -11. 

Curtis,  A  Textbook  of  General  Botany,  Chapters  VII  and  VIII. 

Leavitt,  Outlines  of  Botany.  Bryophytes,  page  108,  Pteridophytes,  | 
204. 


CHAPTER   XXVII 

THE  CONIFERS  (aYMNOSPERMS) 

266.   General  Characteristics.  —  In  passing  from  the  ferns 
to  the  conifers,  usually  known  as  evergreens,  we  go  from  a 


Figure  406.  —  Conifers. 
At  center  and  left.     Note  their  undivided  trunks. 


lower  to  a  higher  order  of  plants.      With  the  exception  of 
the  corn  and  bean,  none  of  the  plants  studied  up  to  this 

376 


ri.xL'  v// /•;/■: 


:;:: 


Figure  407.  —  Staminate  Strobili  of 
Pine. 


time  bears  seeds,  but  all  reproduce  by  spores  or  by  ferti- 
lized eggs.     Most  of  the  evergreens  are  seed-bearing  tn 
which  vary  in  size,  but  which  are  alike  in  having  trunks 
that  taper  from  the  base 
to  tip  without  dividing. 
Such   trunks  are   called 
excurrent.       The     ever- 
green    group     contains 
the  largest  plants  in  the 
world   and   those   which 
live  to  the  greatest  age. 
Their  foliage  is  usually 
composed  of  dark  green, 
needle-like  leaves  which 
remain  attached   to  the 

tree  for  two  or  three  years.     Thus  the  trees  always  have 
some  foliage  and  so  are  termed  "evergreen." 

267.  Pine  Tree.  —  The  pine  illustrates  the  plants  of  this 
family.  The  pine  has  all  the  parts  of  a  dowering  plant 
—  stem  (trunk),  branches,  roots,  leaves,  seed-producing 

organs,  and  fruit  (cones). 

Stem.  —  The  trunk  does  not 
divide,  —  a  marked  character- 
istic of  evergreens.  In  a  forest 
where  trees  arc  crowded  together 
and  there  is  in  consequence  a 
struggle  t<>  get  Light,  'he  trunks 

grow  tall  ami  m08t  of  the 
branches  are  near  the  top. 
A  cross  section  of  a  stem  shows  a  scries  of  rings,  known 
as  annual  rings,  by  which  the  approximate  age  of  the  t: 
can  be  told.  In  the  spring  when  all  the  conditions  arc  at 
their  best  and  growth  is  rapid,  the  cells  «»!'  the  tree  art- 
large  and  thin-walled,  strength  being  sacrificed  to  size. 


Figure  408.  —  Young  Cone 
of  Pine. 


378 


CONIFERS 


Figure  409.  —  Ripe  Cone  of 
Pine. 


But  in  the  fall  or  during  a  dry 
time  in  summer,  the  cells  formed 
are  much  smaller  and  the  walls 
thicker.  These  small  cells  which 
show  most  plainly  make  up  the 
annual  ring.  During  a  season 
in  which  long,  dry  periods  occur, 
more  than  one  ring  may  be  made. 
From  the  center  to  the  bark  ex- 
tend lines  which  are  made  of 
pith  and  are  known  as  medul- 
lary rays.  The  part  of  the 
stem  where  increase  in  thick- 
ness takes  place  is  just  under 
the  bark. 
Branches.  —  The  branches  leave  the  stem  almost  hori- 
zontally and  nearly  in  a  circle  around  the  trunk  of  the 

tree.     In  the  pine  they 

curve  upward,  but  each 

kind   of   evergreen    has 

its  own  habit  of  curva- 
ture in  its  branches. 
Leaves.  —  The  leaves, 

called  needles,  are  long, 

slender,  and  flattened  on 

one   side.      They   grow 

in  bundles  of  two,  three, 

four,    or    five     needles, 

according    to    the    kind 

of    pine.      The    leaves, 

which    are     borne     but 

once  in  a  place,  remain 

on  the  tree  from    two    to    five  years  and   then   fall   off, 

leaving  the  branches  bare  except  near  the  ends. 


Figure  410. — Other  Cones. 
a,  arbor  vitae ;    b,  hemlock. 


PISE    TREE 


379 


Moots.  —  The  roots  of  the  pine  vary  according  to  the 
kind  of  pine  and  according  to  the  soil,  but  they  are  alwa 

extensive. 

Seed-producing    Organs. — Early    in     the    spring,    two 

kinds  of  cones  are   found  on  the  oew  shoots  which   grow 
from  the  terminal  buds. 

One  kind  looks  like 
short  catkins,  and  these 
cones  are  borne  in  clus- 
ters near  the  base  of  the 
shoot.  They  consist  of 
scales  arranged  spirally 
around  the  central  axis. 
Each  scale  bears  two 
pollen  sacs.  These  are 
the  staminate  cones 
(Latin  sta,  stand)  or 
strobili.  They  wither 
soon  after  shedding  their 
pollen,  although  they 
may  remain  on  the  tree 
for  a  year.  The  other 
kind  of  cone  is  short  and 
thick,  and  is  found  at 
the  tip  of  the  shoot  or 

on  the  Side  of  the  shoot     The  splendid  trunk  in  the 

.,       ..  r™  •     •     .1  is    that    of   a   cucumber    tree.      (Hugh 

near  the  tip.     1  his  is  the       p   Baker  \ 
carpellate  cone  (female 

strobilus),  which  is  made  up  of  scales  arranged  spirally 
around  a  central  axis.  Bach  scale  near  its  base  bears  two 
ovules.  When  the  pollen  is  ripe,  each  grain,  being  pro- 
vided with  winjrlike  air  sacs,  is  easily  blown  about  by  the 
wind.  Some  of  the  pollen  sifts  into  the  carpellate  cone 
through  the  spaces  between  the  scales,  which  at  this  time 


Figure  411.-- A  Virgin  Forest  of  Mixed 
Hard  Woods  and  Conifers  in  North- 
ern Pennsylvania. 


Figure  412. —  Lumbering  in  New  York. 


Figure  413.  —  Fire  Slash. 
The  scene  of  a  great  destructive  fire  in   1908. 


HABITAT 


381 


are  separated  slightly. 
Then  the  scales  close 
together,  the  cones  turn 
downward,  and  con- 
tinue to  grow  for  sev- 
eral months  (Figures 
407-410). 

Fruit.  —  During  the 
next  year,  the  pollen 
grains  which  are  shut 
up     inside     the     scales 


Figure  414. 


Waste  Land  in  Pennsyl- 
vania. 

The  year  previous  to  the  taking  of  this 
grow   into   pollen   tubes      photograph  this  land  was  covered  with  a 
t      c     ,.-,.  ,,  virgin   forest    as   shown    in    Figure   411. 

and     fertilize     the     egg      Logging  has  been  followed  by  fire,  which 

destroyed  the  humus  and  much  of  the 
surface  soil,  making  the  tract  a  barren 
waste  upon  which  it  will  be  impossible 
to  grow  another  such  forest  for  many 
years.  Pennsylvania  alone  has  several 
millions  of  acres  of  such  waste  land 
covered  formerly  by  splendid  virgin  forest. 


cells  which   develop   in 
the   ovules.      From   the 
fertilized   e^ors  the  em- 
bryo  pines  develop. 
When  the   cones  are 


about  two  years  old  the 
scales  open,  and  allow  the  seeds  to  drop  out.      Bach  seed 
is  provided  with  a  wing  by  which  it  is  blown  about,  for 

the  pine  depends  <>n  the 
wind  to  Bcatter  its  seeds 

as    well     as     its     pollen. 

Because  1 1  ds  li<"  on 

the  scale  without  being 

Inclosed  in  an  <»\  av\  .  all 

these  plants  are  called 
gymno9p<  rm%       < ( rreek, 

gymnoS)  naked  :  >/"  mt<u 
-■••■(I  >. 
268.   Habitat  — The 

Figure  415.  —  Waste  Land. 

After  the  fire  had  passed  over  the  region     evergreens        ?row        m 
shown  in  Figure  413.  -  1 1 1 <  1  \    soil    in    temperate 


382 


CONIFERS 


Figure  416.  —  Fire  Train  in  the  Adirondacks. 


Figure  417.  —  Nursery  Where  Young  Trees  are  Started. 


RELATED  FORMS  OF   CONIFERS 


383 


or  in  cold  climates,  but  ;i  lew  <>f  them  occur  where  it 
is  very  warm.  The  finest  evergreen  forests  in  the  world 
are  found  in  the  western  part  of  North  America,  on  the 
slopes  facing  the  Pacific  Ocean. 

269.  Related  Forms  of  Conifers. — •  Hemlocks,  spra  .  firs, 
and  balsams  have  smaller,  flatter  needles  than  the  pines 
and  they  are  not  arranged  in  bundles.  Cedars  have  scale- 
like leaves.  Larch  and  cypress  trees  shed  their  Leaves  in 
the  fall,  but  in  other  respects  are  much  like  the  pin 


FIELD   STUDY   OF   GYMNOSPERMS 

Most  of  the  work  in  connection  with  gymnosperma  Bhould  \«-  d 
out  of  doors.     The  student  Bhould  learn  to  know  by  Bight  all  tin-  local 
native  evergreens  and  those  commonly  planted  for  ornament.     He  Bhould 
note  the  method  of  branching  and  the  character  of  the  trunk  compared 
with  other  trees.     He  should  observe  the  position  <»f   the  cones  on  tin- 
branches  and  be  able   to   give  the  reasons  therefor.     In  the  spring  he 
should  look  for  the  male  and  female  cones  or  strobili,  and  for  leaf  buds  in 
the  winter.     He  should  examine   the   leaf  sears  and  the  external  ru 
which  mark  a  year's  growth,  and  decide  how  many  years  each  tree  k<  • 
its  leaves.     He  should  note  the  arrangement  of  the  haves  on  the  brand] 
the  annual  rings  in  the  wood  and  their  relation  to  the  grain  of  the   wood, 
the  resin  on  wounds,  the  curvature  of  the  branches,  and  the  other  : 
tures  readily  observed. 


STUDENT    REPORT 


N  t:  l  I  >  I  B8 

MM.I  B 

A  i.i  i:i:\  \  i  i:  • 

Nbedlbs 

Needles  is 

.  i  - 

-.   \i  ■  i  no. 

in  m « i  bs 

i.  \ 

3  m 

Hemlock 

White  Pine 

Larch 

Cedar     . 

Spruce    . 

Etc.    .     .     . 

384 


CONIFERS 


LABORATORY 

In  the  laboratory  examine  a  cross  section  of  the  stem  to  see  the  dif- 
ference in  the  cells  grown  in  the  early  and  in  the  late  part  of  a  season. 
Note  the  pith  and  medullary  rays.  If  specimens  are  available,  examine 
sections  of  wood  from  different  trees.  Make  a  collection  of  the  woods 
found  in  the  vicinity.  Examine  scales  from  staminate  and  carpellate 
cones.  With  the  microscope  examine  pollen  of  pine.  Draw  and  describe 
all  the  rays. 

270.  Economic  Importance.  —  The  value  of  the  gym- 
nosperms  can  scarcely  be    overestimated.       Most    of   the 


Figure  418.  —  Planting  Young  Trees  in  the  Adirondacks. 

trees  are  sawed  into  lumber  for  building  purposes,  but 
some  of  them  are  used  in  their  natural  form  for  telegraph 
poles,  masts  of  ships,  and  timbers  of  mines.  Wood  pulp, 
from  which  most  of  our  paper  is  made,  is  produced  from 
small  spruce  trees.  The  by-products  of  this  group  of 
trees  are  of  great  value.  From  the  pine  come  tar,  pitch, 
turpentine,  and  resin,  while  the  bark  of  the  hemlock  was 
formerly  extensively  used  in  tanning  leather. 


IMl'oUTANCE  OF   FORESTS 


385 


The  forests  of  the  United  States  cover  about  550,000,000 
acres,  or  more  than  one  fifth  of  the  total  area. 

"Generally  speaking,  countries  having  over  twenty  per 
cent  of  wood  lands  have  fores!  resources  sufficient  to 
supply  their  lumber  industries  and  their  firewood  con- 
sumption, provided  that  such  area  is  properly  stocked 
and  conserved."  —  Schenck,  "Fores!   Policy,"  page  71. 

Yellow  pine,  which  supplies  one  third  of  the  Lumber 
consumed  in  the  United  States,  ranks  first  in  value  ;   white 


Jk.jL. 


»»•»?■.«-— ^  j M^   mt  +  ta^*-.  . 


4 


Figure  419. — Young  Plantation  in  the  Adirondacks. 


pine,  which  formerly  supplied  the  greatest  amount,  ranks 
second;   and  Douglas  fir,  third. 

271.  Related  Topics. —  Hardwood  forests  are  compos 
of  trees  which  have  broad  leaves  and  flowers  with  typical 
stamens  and  pistils.  Such  trees  grow  either  alone  or  in 
tracts  containing  many  evergreens,  Maple  trees  supply 
sugar  and  syrup,  the  industry  being  important  in  Ohio 
and  Vermont.  Other  hardwood  trees  yield  fuel,  Lumber, 
and  nuts. 

272.  Importance  of  Forests. —  Forests  are  of  the  test 
importance  in  preventing  floods  caused  by  the  rapid  melt- 
ing of  ice  and  snow.     The  snow  melts  more  Blowly  in  the 


386 


CONIFERS 


woods,  not  only  during  a  midwinter  thaw,  but  also  in  the 
spring,  and  the  soft,  porous  character  of  soil  causes  it  to 
absorb  much  water.  This  results  in  springs  and  rivers 
being  fed  uniformly  during  the  summer.  Floods  and 
freshets  can  often  be  traced  largely  to  denuded  hills  along 
the  streams,  because  hills  without  forests  have  soil  poorly 


Figure  420. — Young  Plantation   16  Years  after  Planting. 


fitted  to  prevent  the  water  from  running  down  faster 
than  it  can  be  carried  away.  Floods  and  freshets  each 
year  do  millions  of  dollars'  worth  of  damage  in  the  de- 
struction of  bridges,  buildings,  and  other  property. 

Another  loss  occurs  in  the  washing  away  of  the  most 
valuable  form  of  soil  from  the  hills,  when  the  water  flows 
off  rapidly.     Not  only  is  the  soil  that  is  left  useless  for 


IMPORTANCE  OF  FORESTS 


387 


Figure  421 .  —  Pollen 
of  Pine. 


agriculture   for   many    years,  l>ut   that    carried    into   the 
streams  clogs  harbors  and  channels,  making  it   accessary 

to  spend  large  sums  in  dredging. 

Forests  arc  destroyed  not  only  by  lumbering  operations, 
but  also  by  fires,  many  of  which  are  caused  by  carelessm 
Forest  fires,  in  addition  t<>  destroying 
the  trees,  render  large  territories  useless 
for  agriculture  by  burning  up  the 
humus,  or  organic  part  of  the  soil.  So 
great  is  the  destruction  and  waste 
caused  by  forest  tires,  that  the  national 
and  state  governments  have  taken  measures  to  prevent 
them.  Forests  are  now  patrolled  daily  during  parts  of 
the  }Tear  and  apparatus  for  fighting  fires  is  always  in 
readiness. 

In  addition,  the  government  is  setting  out  thousands  of 
young  trees  and  protecting  them  in  an  effort  to  re-fon 
bare  territory,  especially  around  the  headwaters  of  rivers. 
Where  forests  still  exist,  the  government  is  buying  them 
in  order  that  they  may  not  be  destroyed.  Such  tracts 
are  called  forest  reserves. 

In  European  countries  the  study  of   forestry  lias  been 
carried  on    for  a  long    time.     Their    forests  are    made    ,i 

source  of  revenue,  but  all  the  1 1 
are  never  cut  in  a  single  season, 

and  planting  keeps  pace  with  cut- 
ting. Scientific  forestry  is  now 
practiced  on  aboul  i"1','  of  the 
public  forests  of  the  I  Ihited  States 
and  on  about  2%  of  the  woodlands  privately  owned. 
Only  about  one  fifth  of  the  wooded  area  of  the  United 
States  is  under  government  control.  New  York  Si.it.-  is 
taking  steps  to  preserve  her  forests  and  also  to  re-forest 
large  tracts  which  have  been  out  over  (Figures   IIs    120  >• 


■  "     "H. 

..-'. 

N  n 

y 

\ 

V^ 

e£    '..'. 

\ 

Figure  422.  —  Seed  of  Pine. 


388  CONIFERS 


SUMMARY 


The  conifers  belong  to  a  class  of  the  higher  plants. 
They  have  periods  of  active  and  less  active  growth,  both 
together  resulting  in  the  appearance  of  annual  rings. 
Because  their  seeds  are  not  entirely  inclosed  in  an  ovary, 
but  lie  uncovered  on  a  scale,  they  are  called  gymno- 
sperms.  Conifers  are  of  great  economic  importance,  for 
they  supply  much  of  our  lumber,  tar,  pitch,  and  all  our 
turpentine  and  resin.  Hardwood  trees  grow  with  the 
evergreens.  They  belong  to  many  families  of  flowering 
plants  and  furnish  lumber,  fuel,  and  nuts.  Forests  help 
to  regulate  the  flow  of  streams  and  they  prevent  the 
washing  away  of  the  soil. 

QUESTIONS 

How  are  gymnosperms  like  other  plants  ?  How  do  they  differ  from 
other  plants  ?  What  kind  of  a  trunk  is  characteristic  of  gymnosperms  ? 
How  does  a  tree  which  grows  in  a  forest  differ  from  one  which  grows 
in  an  open  field  ?  Why  ?  What  are  annual  rings  ?  How  are  they 
formed  ?  Describe  the  branches  ;  the  leaves ;  the  roots ;  the  cones  or 
strobili ;  the  fruit.  What  is  a  sporophyte  ?  Name  the  gymnosperms. 
Make  a  list  of  the  uses  to  which  lumber  is  put.  What  other  products 
come  from  the  evergreen  forests  ?  In  what  ways  are  forests  beneficial  ? 
What  are  the  governments  doing  to  protect  them  ?  What  regions  in 
your  own  state  are  covered  with  forests  ? 

REFERENCES 

Government  pamphlets  and  bulletins. 
Hough,  American  Woods. 
Keeler,  Handbook  of  Trees. 
National  Geographic  Magazine. 
Sargent,  Trees  of  North  America. 
Schenck,  Forest  Policy. 


CIIAI'TKR    XXVIII 


PECULIARITIES    OF   PLANT   LIFE 

273.  Unusual  Plants. — hi  order  to  live,  all  plants  must. 
have  conditions  favorable  to  their  vital  processes,  and 
many  of  them  develop  special  modifications  which  aid  the 
plant  in  the  struggle  for  existence.  Sonic  of  the  modi- 
fications already  studied  in  this  book  arc  the  arrangement 
of  leaves  or  the  length 
of  petioles  to  secure  air 
and  light ;  the  presence 
of  color,  odor,  and  nec- 
tar, devices  to  attract 
insects  and  thus  secure 
the  pollination  of 
flowers ;  and  the  use 
of  wings,  pappus,  and 
hooks  to  secure  the 
distribution  of  seeds. 
Many  of  the  carnivorous 
and  parasitic  plants  are 

remarkable  for  the  modifications  which  make  it  possible 
for  them  to  obtain  nitrogen,  an  clement  lacking  in  the 
food  supply  of  their  particular  environment. 

Tfie  Pitcher  Plant.  —  The  leaves  of  this  plant   form  a 
sort  of  vase  which   retains   water   in    the   bottom.      When 

insects  crawl  into  the  leaf,  their  escape  Is  prevented  by 
hairs  which  grow  around  the  opening  on  the  inside  and 
point  downward,  and  the  unfortunate  victim,  exhausted 

389 


Figure  423. 


Photograph  of  Pitcher 
Plant. 


390 


PLANT    PECULIARITIES 


by  his  struggles  to  get 
out,  falls  into  the  water 
and  is  drowned.  When 
the  bodies  decay,  the 
plants  secure  the  nitro- 
gen which  they  are  un- 
able to  get  through  their 
roots. 

The  Sundew.  —  This 
plant  has  round  leaves 
covered  with  long  glandu- 
lar hairs  which  secrete  a  sticky  substance.  When  an 
insect  alights  on  a  leaf,  the  hairs  bend  over  and  hold  the 
victim  until  it  dies,  the  secretions  of  the  plant  meanwhile 
digesting  the  soft  parts  of  the  insect.     When  the  leaf  has 


Figure  424.  —  Leaves  of  Pitcher 
Plant. 


Figure  425.  —  Photograph  of  Sundew. 


UNUSUAL  PLANTS 


391 


absorbed  this  digested  food,  the  hairs  release  the  remain- 
ing parts,  which  then  fall  off,  and  the  hairs  resume  their 

usual  position. 

Venus*  Fly-trap.  — -  This    plant    has    another   waj    to 

catch  insects.      The    leaves  end    in    a    traplike    device    in 

two  parts  which  lie  flat  like  the  Leaves  of  a  1 k.     When 

an  insect  alights  on  one 
side,    the    other    clo 
quickly  and  confines  the 


Figure  426.  —  Diagram  of  Sundew.      Figure  427.   -Venus's  Fly-trap. 

fly  by  bail's  on  the  edge  which  interlock.  Digestion  and 
absorption  soon  take  place,  after  which  the  Leaves  lie  flat 
again,  ready  for  another  insect   visitor. 

Indian  Pipe.  —  Although  it  produces  flowers  and  seeds, 
this  plant  has  no  chlorophyll  and  BO  is  a  waxy  white  in 
appearance.     It  gets  its  nourishment  from  decayed  organic 


392 


PLANT    PECULIARITIES 


matter,  usually  wood, 
just  below  the  soil.  A 
fungus  which  grows  on 
the  roots  helps  them  to 
absorb  this  prepared 
food. 

Mistletoe.  —  We  are 
most  familiar  with  this 
plant  as  a  part  of  our 
Christmas  decorations. 
Mistletoe  has  chlorophyll 
and  so  is  able  to  manu- 
facture its  own  food,  but 
it  has  no  roots  for  ab- 
sorbing water,  making  it 
dependent  on  a  larger 
plant  for  this  necessary 
part  of  its  vital  condi- 
tions. The  plant  possesses  absorbing  organs  which  pierce 
the  bark  of  the  trees  upon  which  it  grows.  As  a  result  it 
does  much  injury  to  the  trees  by  using  the  water  which 
they  need  for  their  own  life  processes.  In  the  South, 
for  instance,  the  mistle- 
toe is  regarded  as  a 
great  pest. 

274.  Movements  of 
Plants.  —  Most  plants 
move  slowly  and  only 
in  response  to  one  of 
several  stimuli.  Touch, 
or  contact,  is  the  stimu- 
lus in  the  case  of  sun- 
dew and  Venus's  fly- 
trap, both  of  which  are  Figure  429.  —  White  Waterlily. 


Figure  428.  —  Photograph  of  Birch 
Roots. 

Growing  over  the  surface  of  a  boulder. 


PLAXT   SOCIETIES 


393 


peculiar  in  moving  quickly.     Tendrils  curve  undei  the 
influence  of  the  same  stimulus,  but  they  move  slowly. 

Light  and  darkness  arc  universal  stimuli.  Flowering 
plants  move  toward  the  Light,  it"  it  docs  nol  surround  them 
evenly  on  all  sides.  Window-growing  plants  Bhow  this. 
Plants  like  potatoes,  which  sprout  in  a  cellar,  grow  many 


Figure  430.  —  Waterlilies  —  Hydrophytes. 


feet  to  get  into  the  light.  Darkness  causes  plants  like 
clover  and  oxalis  to  close  their  Leaves. 

Moisture  is  a  stimulus  which  affects  the  roots  of  a  plant, 
as  is  shown  in  Figure  428. 

275.  Plant  Societies.  —  The  term  plant  society  is  applied 
to  any  collection  of  plants  which  grow  under  similar  con- 
ditions. The  trees  of  the  forests,  and  thegrass  and  weeds 
of  our  lawns,  are  typical  example-.  In  mosl  cases  water, 
or  the  lack  of  it,  is  the  basis  \'^r  classifying  or  grouping 
plants  in  societ  ies.  Plants,  Like  some  alga*.  Live  submerged 
in    the    water,    while     others.    Like     the    waterlilies.    Live 


394 


PLANT    PECULIARITIES 


partly  in  the  water,  lifting  their  leaves  and  flowers  into 
the  air. 

Plants  which  live  in  the  water  are  called  hydrophytes 
(hy'dro-fltes :  Greek,  hydor,  water;  phyton,  plant).  If 
such  plants  have  roots,  they  are  little  more  than  holdfasts, 
for  the  hydrophytes  do  not  need  organs  of  absorption. 
Most  of  the  members  of  this   plant   society   are  without 


Figure  431.  —  Cat-tails  and  Arrow-leaf. 


mechanical  tissue,  for  the  water  holds  them  firmly  on  all 
sides.  The  alg?e  lack  a  conducting  system  as  well,  for 
their  source  of  food  is  all  about  them.  Waterlilies  get 
their  oxygen  and  much  of  their  carbon  dioxide  from  the 
air  through  their  leaves,  which  float  on  the  surface  of  the 
water  with  the  stomata  on  top.  Air  passages  in  the  long, 
slender  steins  convey  air  to  the  roots  which  lie  in  the  mud. 
Hydrophytes  which  lie  under  water  have  their  leaves 
finely  divided  to  offer  as  much  surface  as  possible  to  the 
water  and  thus  secure  a  full  supply  of  oxygen. 


PLANT  SOCIETIES 


395 


Figure  432.  —  Giant  Cactus. 


Figure  433.-    Sage  Brush. 


396 


PLANT    PECULIARITIES 


Figure  434.  —  Diagram. 

Section  of  the  epidermis  of  agave,  "a 
xerophytic  plant.  Compare  this  sec- 
tion with  the  section  of  the  bean  leaf 
in  Figure  265. 


Plants  which  live  in 
desert  regions,  of  neces- 
sity, have  to  live  on  little 
water.  They  are  called 
xerophytes  (zeVo-fites  :. 
Greek,  xeros,  dry ;  phyton,. 
plant).  Xerophytes  usu~ 
ally  have  long  roots  so- 
that  when  moisture  is- 
present  they  may  gather 
it  rapidly.  Many  forms 
have  little  surface  ex- 
posed to  the  air ;  the  branches  are  few,  and  there  are  no 
leaves.  The  stem,  which  is  green  in  color,  perforins  the^ 
work  of  photosynthesis.  To  conserve  their  water  supply 
further,  the  xerophytes  have  a  thick  epidermis  and  few 
stomata.  These  plants 
are  an  admirable  illustra- 
tion of  making  the  most 
of  what  one  has. 

Desert  plants  live  in 
regions  where  it  is  usu- 
ally both  hot  and  dry, 
but  plants  of  the  Arctic 
Regions  have  many  of 
the  same  modifications, 
only  in  a  lesser  degree. 
Much  of  the  time  severe 
cold  prevents  the  roots 
from  absorbing  water, 
and  the  plant  must  keep 
what  it  already  possesses. 
Some  of  the  Arctic  plants,  Figure  435.  —  Bull  Thistle. 

therefore,     have     leaves  A  mesophyte  weed. 


PLANT  SOCIETIES 


397 


which  roll  to  reduce  the 
surface  and  have,  in  ad- 
dition, a  coating  of  hairs, 
both  devices  for  retard- 
ing transpiration. 

Most  of  the  plants 
which  we  see  and  which 
live  where  there  are  no 
great  extremes  of  heat 
or  cold  and  where  it  is 
neither  wet  nor  dry  are 
called  mesophytes  (mez'o- 
fites  :  Greek,  mesos, 
middle  ;  phi/ton,  plant). 
They  have  few  charac- 
teristics in  common,  but 
all  have  roots  suited  to 
the  soil  in  which  they  grow,  and  leaves  which  in  shape 
and  arrangement  serve  the  purposes  of  cadi  plant  better 


Figure  436.  —  Lady  Slipper. 


I'fc)    Mi 

>  si 

Ml         B  S 

r«? 

•**?! 

^B^^B  w^.                ^ffC 

[j|  \^  V 

Br    ^^^fl| 

p>^ 

^mZ^i 

LM.i^mk 

y+-  jf 

Figure  437. —  Long-spurri 


398 


PLANT    PECULIARITIES 


than  any  others  would  do.      Examples  of  this  are  the  nar 
row,   upright  leaves   of  the   grass,  which   grows  thickly 


~&  1/ 


-    -. 


.     - 


Figure  438.  —  Mistletoe. 
A  semi-parasite.     This  tree  has  no  leaves. 


crowded  together,  the  broad  leaves  of  the  trees,  and  the 
leaves  of  the  ivy,  which  grows  on  walls,  arranged  like  a 
mosaic.      Many   divisions   of   the    mesophytes    might   be 


PLANT  SOCIETIES 


made,  for  some  prefer  sunn \  local  imis,  <>t  hers  shadv  plaot 
and  so  on. 


Plants  which  live  in  tin 
called  epiphytes  (ep'l-fites  : 
plant)  because  they  usu- 
ally attach  themselves 
to  the  stem  of  a  larger 
plant.  Their  modifica- 
tions consist  of  one  kind 
of  roots  for  fixing  them 
to  their  support  and 
another  capable   of   ab- 


air  make  up  another  group, 
( ircck.  epii  upon  :   phyton^  a 


sorbing      and 


storing 


water.  The  latter  or- 
gans are  called  velamens 
and  are  composed  of 
spongy  tissue.  They 
are  situated  on  the  out- 
side of  the  plant,  soak 
up  rain  and  dew  and 
conduct  it  to  an  inner 
region  where  it  is  used 
as  the  plant  needs  it. 
Velamens  can  also  ab- 
sorb moisture  from  the 


Figure  439.  —  Diagra- 

Sectional  view  of  a  branch  infected 
with  mistletoe,  showing  the  relation  be- 
tween the  parasite  and  host  ;  a.  branch 
of  host  tree  ;  b.  mistletoe ;  c.  primary 
sinker;  d,  sinker  from  cortical  root; 
e,  /,  cortex  of  soft  bark  ;  g,  cambium 
or  growth  ring;  /;.  wood  of  branch. 
The  starving  and  dwarfing  of  the  branch 
beyond  the  mistletoe  is  shown  at  ;'. 


air.  The  epiphytes  are 
characteristic  of  the  tropics,  where  the  air  IS  full  of 
moisture  and  where  rains  fall  frequently.  In  OUT 
own  part  of  the  world,  lichens  lia\  imewhal  tin- 
same  habit,  and  orchids  in  greenhouses  are  another 
example. 

The  study  of  plants  which  deals  with  their  distribution 
and  the   factors  which    govern  it   is  called    plant  < 
(e-kol'o-jy  :    (J reck,  oikos,  home;    hgo$,  talk). 


400  PLANT    PECULIARITIES 

276.  Plant  Succession.  —  When  a  swamp  is  drained,  a 
forest  cleared,  or  a  desert  irrigated,  plant  conditions  are 
changed.  Thus  it  becomes  impossible  for  some  plants  to 
thrive  in  their  former  habitat,  and  possible  for  others  to 
grow  where  before  they  could  not.  The  replacing  of  one 
plant  society  by  another  is  termed  plant  succession.  When 
a  forest  is  cleared  and  the  tract  burned  over,  the  plant 
called  fireweed  appears  in  large  numbers,  even  if  a  culti- 
vated crop  is  planted.  After  a  year  or  two  the  fireweed 
gives  way  to  a  growth  of  blackberry  and  raspberry  bushes, 
which  are  later  replaced  by  grasses  and  weeds  of  various 
kinds. 

Another  example  of  plant  succession  is  seen  in  regions 
covered  by  fresh  lava  from  a  volcano.  At  first  nothing 
grows.  Probably  bacteria  and  fungi  appear  before  other 
plants  are  noticed,  but  lichens  are  usually  the  first  to  be 
observed.  These  die  and  decompose,  and  their  remains, 
together  with  bits  of  lava  loosened  by  frost,  wind,  or 
water,  accumulate  in  depressions  and  form  a  soil  in  which 
mosses  can  grow.  The  remains  of  the  mosses  add  to  the 
organic  matter  in  the  slowly  increasing  soil,  and,  in  the 
course  of  time,  ferns  and  larger  plants  can  grow.  The 
last  finally  replace  the  mosses  as  they  replaced  the  lichens. 

277.  Summary  of  Our  Interest  in  Plants.  —  Our  first 
interest  in  plants  is  economic,  that  is,  we  think  of  them 
first  in  terms  of  their  usefulness  or  harmfulness  to  us. 
As  every  animal  in  the  world  is  dependent  directly  or 
indirectly  upon  plants  for  food,  it  becomes  obvious  to  what 
a  degree  we  are  benefited  by  the  ability  of  plants  to  make 
food  out  of  the  air  and  the  soil. 

Man  could  live  comfortably  on  what  three  plant  families 
furnish,  —  the  grasses,  which  include  all  the  cereal  foods 
and  sugar;  the  pulse  family,  which  furnishes  most  of  our 
vegetable  nitrogen ;  and  the  rose  family,  which  includes  the 


SUMMARY  OF  OUR  INTEREST   IN   PLANTS     401 

plants  which  furnish  us  our  luxuries  in  the  wav  of  fruits. 
In  eating  animal  products,  man  is  still  dependent  apon  tin- 
grass  family  to  furnish  food  for  the  cattle  from  which  be 
obtains  meat,  milk,  cheese,  and  butter.  For  clothes,  man 
depends  indirectly  upon  plants  for  the  Leather  and  woo] 
of  the  domestic  animals,  and  directly  for  cotton  and  linen. 


F\'^l 

.         40*1 

W* 

f    ;£#"            v«*tfd 

%x*, 

5  ■    "^* 

1 

i 

■:  '$$'$>'  JIB 

»tfV  Mi 

« 

• 

; 

■ 

*"  ^^2St^t  * 

Iflttr' - 

Figure  440.  —  Tropical  Vegetation. 
Note  how  different  the  plants  are  from  ours. 

Plants  are  the  source  of  many  of    the   materials  out   of 
which  houses  are  made  and  furnished. 

Some  plants  (bacteria)  cause  disease,  while  still  others 
provide  remedies  with  which  to  cure  diseases.  Plants 
please  our  eyes  as  we  travel  about.  They  keep  up  tin' 
supply  of  oxygen  in  the  air  ;  they  rid  the  air  of  tin1  carbon 
dioxide  which  we  have  cast  off;  they  provide  employment 
for  millions  of  men  who  raise  food  plants,  manufacture 
them  into  food,  and  distribute  them  throughout  the  world  ; 


402  PLANT    PECULIARITIES 

and  they  employ  other  millions  in  the  production  of  cotton 
plants  and  cotton  cloth  for  our  clothing. 

The  farmer  who  raises  plants  has  an  interest  in  knowing 
what  kind  of  soil  and  climate,  how  much  water,  air,  and 
light  each  kind  of  plant  needs  to  yield  him  the  best  results. 
To  this  end  he  has  to  know  something  about  the  habits  of 
plants  in  general,  and  about  their  enemies  and  their  dis- 
eases. He  has  learned  by  experience  that  some  plants 
grow  better  when  planted  in  hills  ;  others  in  drills,  and 
still  others  sown  broadcast.  He  is  still  trying  to  find  the 
best  kind  of  plant  food  for  each  plant,  and  the  method  of 
cultivation  which  best  enables  plants  to  get  their  full 
supply  of  food  and  moisture,  and  he  is  still  fighting  weeds 
which  deprive  the  useful  plants  of  their  share  of  food, 
water,  and  light.  Yet  he  is  conscious,  if  he  stops  to  con- 
sider, that  he  cannot  make  a  plant  grow.  His  part  is  to 
create  good  vital  conditions. 

We  are  interested  in  the  work  of  men  who  are  trying 
by  cross-pollination,  grafting,  and  selection  to  reduce  the 
undesirable  parts  of  plants  and  to  increase  their  capacity 
for  food,  storage  or  whatever  we  find  desirable.  Luther 
Burbank  has  made  many  experiments  along  these  lines, 
especially  in  increasing  the  number  of  fruits  on  trees  and 
in  reducing  the  size  of  the  seeds  in  berries. 

278.  Scientific  Interest.  —  In  addition  to  practical  in- 
terests, that  is,  besides  the  supreme  importance  of  plants 
to  man  and  his  dependence  upon  them,  there  is  another 
interest,  —  that  of  the  scientist  in  plants  as  organisms. 
The  scientist  studies  how  plants  are  like  animals ;  how 
they  differ  from  them ;  how  each  is  dependent  upon  the 
other  for  waste  products ;  how  plants  depend  upon  animals 
for  the  pollination  of  their  flowers  and  the  scattering  of 
their  seeds,  and  how  the  plants  make  use  of  the  wind  and 
water  for  the  same  purposes. 


SCIENTIFIC  IX  TERES  T 


403 


He  studies,  too,  the  increasing  complexity  of  plants 
from  the  simple,  one-celled  plants  dependent  upon  water 
for  existence  up  through  the  plants  which  are  becom- 
ing accustomed  to  living  ou  land,  and  finally  to  the 
which  have  complex:  systems  and  complex  Sowers.  He 
finds  that  all  are  related,  and  the  more  be  Learns  about 
them,  the  more  interesting  does  he  find  their  relationshi] 
He  is  interested  in  seeing  how  the  changfe  from  water  to 
land  calls  forth  changes 
in  structure  to  fit  the 
new  environment ;  how 
in  land  plants,  each  one 
has  adapted  itself  in 
form,  size,  arrangement 
of  leaves,  and  so  on,  to 
make  the  best  possible 
use  of  the  air  and  water 
which  it  is  able  to  pro- 
cure. 

In  trying  to  find  the 
causes  of  such  varia- 
tions of  plants  the 
scientist  performs  many 
experiments,  often  upon 
the  smallest  plant,  for  size  and  complexity  arc  no  Indication 
of  the  interest  which  may  center  in  a  plant  structure.  Bac- 
teria, for  instance,  which  are  the  simplest  and  smallest  of  all 
plants,  are  being  st  udied  more  to-day  than  any  of  the  others. 

Every  year  adds  to  our  knowledge  of  the  nature  of 
plants,  their  relations  to  each  other  and  to  man.  Besides 
these  relations  due  to  their  surroundings,  plants  bear  I 
wards  each  other  the  relation  of  dependence  and  inde- 
pendence, which  we  have  discussed  under  parasitism  and 
symbiosis. 


Figure  441.  —  Calla. 

From  an  X-ray  photograph.     One  of 
the  new  ways  of  studying  plants. 


404  PLANT    PECULIARITIES 

Plant  life  itself  remains  a  mystery.  The  poet  Tenny- 
son has  given  expression  to  the  thoughts  of  those  who 
have  tried  in  vain  to  solve  the  many  problems  which  have 
arisen  in  connection  with  the  study  of  plant  life. 

"  Flower  in  the  crannied  wall, 
I  pluck  you  out  of  your  crannies. 
I  hold  you  here  in  iny  hand, 
Little  flower,  root  and  all. 
But  if  I  could  understand 
What  you  are,  little  flower, 
Root  and  all,  and  all  in  all, 
I  should  know  what  God  and  man  is." 

LABORATORY 

To  show  the  response  of  stems1  to"  gravity,  place  seedlings  or  young 
plants  in  unnatural  positions  and  note  their  effort  to  right  themselves. 
To  show  the  response  to  light,  examine  a  potato  from  a  dark  cellar,  which 
has  sprouted  in  the  spring  ;  a  plant  that  has  been  allowed  to  grow  towards 
the  light  in  a  window  ;  the  bending  of  seedlings,  and  the  like.  For  the 
storage  of  food,  examine  all  the  common  garden  vegetables  and  test  them 
for  the  food  which  they  contain.  If  possible,  find  some  vegetables  which 
have  been  kept  for  two  seasons  and  have  produced  seed,  and  note  their 
appearance  after  all  the  food  has  been  used. 

Sprout  slips  of  balsam,  geranium,  and  ivy  to  get  adventitious  roots. 
Show  such  roots  on  the  stem  of  a  tomato  plant  where  it  has  been  allowed 
to  lie  on  the  ground. 

Examine  leaves  in  the  laboratory  and  in  the  fields  to  find  illustrations 
of  all  the  terms  used.  Examine  onions  and  cabbages  for  example  of 
leaves  modified  for  storage,  and  the  onion  also  as  an  example  of  a  re- 
duced stem.  Find  examples  of  all  the  terms  used  in  the  discussion  of 
flowers  and  buds. 


AIM'KXDIX    A 


BIRD    STUDY 


Oxe  of  the  most  fascinat  in--  phases  of  Biology  is  the  Btudy 
of  birds.  This  is  easiest  and  mosl  interesting  during  the 
migrations,  when  the  trees  arc  leafless.  The  early  morning 
is  the  best  time  of  day  for  observing  birds. 

The   following  tables    have  been    compiled  to    help   pupils 
acquire  a  more  intimate  knowledge  of  birds,  —  their  appear- 
ance, habitat,  food,  manner  of  flight,  and  bo  on.     N«»t  only  is 
this  information  valuable   in   itself,  but  there  are   i'rw  tlm 
that  may  be  learned  in  such  a  pleasant  way. 


■Plait  A- 


Brpour    roo  locrmriCATiON  or  Ribki 


s 

I 


i-      S 


8 
is 


5> 

3 

Is- 


3 


I 


1 


Or/ate 


tree 


larvae 


:  Ttaltl 


MX  ■ 


orange 


Ua  \ 


I  VtOB 

t)IJOK 


\'J"f 


r' 


strong 


Purple  nncti 


tree 


fkfca 


I  ■■  :■ :  . 


ti  adab 


! :  i.  0 


tmm 


forked 


Suift 


flying 


insects 


dusKy 


dusky 


dusky 


dusky 


dta  • . 


.'  :• 


Solden  Crooned 
kinglet 


tree . 


.    / 

block 


..  ,/f 


fuscous  fuscous  qreenah  forked 


Bluebird 


tree 


r,  ' 


;.v 


blue 


blue 


?  ..- 


;  I  >,  -i  >■  : 


■-    -», 


//..  r'r 


ground 


lorper 


■:■.■ 
scarlet 


tmuml 


:   ■    "i 


/•'/>/// 


ground 


■.  me 


b*x  h 


rufous 


■ykitr. 


■  ."' 


?' 


trees 
shrubs 


nook  '■■ 


smaller 


• 


90   

b*xM 


.    - 
:  Eft 


r    -xy.t 


trees 


scarlet  scarlet  black    scortet  sooner 


'•;>■>; 


*  Ural  b«*  lum  rtc  JVK«i«a  g/*a  •»  mm*  ttm  r—mr 


105 


406 


APPENDIX  A 


Plate  S- 


Dcuny  Uoodpcckr 


t3 


5uct 


—  Report  for  feeding  station  — 


1 


%> 

§ 


£ 


■*3 

O 

CO 


/to 


Light  Above 
m  bock  doon 


t= 


-C;      O 


Manner  of  — 
comina  to  food— 


i 


13 


-c: 

§> 
in 


Yes 


1 


Tu)0 


"5" 

I 

5 


Yes 


/fairy  rloodpccher 


Suet 


+ 


/to 


Crumbs 
Suet 


/to 


Alignt  Above 
uaiH  doun 
Dead  foremost 


Nuthatch 


Yes 


Yes 


Chickadee 


/to 


Fly  directly 
to  food 


Three 


Brwn  Creeper 


Suet 


Alignt  belocj 
ana  ualh  up 


/to 


One 


Song  sparrou 


Seeds 
Crumbs 


Seeds 

Crumbs 

Suet 


Alight  /tear 
ana  hop  nit 


Four 


No 


House  or 
English  Sparrou) 


Yes 


One 


Yes 


~Robm 


Crumbs 


/to 


tnree 


Yes 


AIM  Near 
UQIKtoif 


Grachle 


Yes 


Tuo 


/to 


Plate  C- 

—  Report  f 

or  Birds  in 

Nesting    Season  — 

3? 

"5 

1 

V) 

4 

Fj$o 

Adults 

Young 

n 
% 

I 

c 

1 

V) 

\ 

1 
N 

1 

1 

1 

? 

-•J 

1 

Robin 

bedpe 

grass  and 
mud  — 

interlaced 

X 

X 

X 

Chipping  Sparrou 

bush 

rootlets 
grass,  hair 

1 1 

X 

X 

X 

Oriole 

dm 

fret 

plant  fibre, 
grass,  string 

uoven 

X 

X 

Grackle 

Voruoj 
Spruce 

grass  and 
uool  — 

inter/acea 

5 

grzen 
oroun 
gray 

li'lonp 

X 

Neadou  Lark 

jrouna 

grass  - 

19 

5 

Oroun 
unite 

rr     r» 

X 

Phoebe 

under 
eaves 

flair,  mud 

feathers 

plastered, 
interlaced 

4 

uhite 

F  " 

X 

Cat  Bird 

oush 

rootlets, 
grass  — 

interlaced 

5 

blue 

V" 

X 

Mourning  Dove 

Horuaj 
Spruce 

grass 

X 

X 

X 

House  Sparrow 

behind 
eave 

hay.  grass, 
feathers  , 

heaped 

X 

X 

BIRD   STl'DY 


40: 


P/ate  D- 

—  Pepori 

on  a 

single  ^a-r  of  Birds  feedm.                   jng- 

to 

1 

I 

\ 

Aumber  of  rimes  eocfi 
/test ling  is  fed — 

Direction  from  uhich 
Adurts  approach  nest 

1 

1 

1 

I 

V 

1 

1 

5 

315 

AM 

X 

uorm 

X 

X 

X 

laun 

X 

3  20 

i  * 

X 

tt 

- 

X 

X 

X 

X 

a 

9  21 

ii 

x 

it 

X 

X 

X 

a 

9  28 

ii 

X 

it 

X 

X 

X 

— 

X 

X 

9  30 

ii 

x 

cherry 

X 

X 

X 

X 

9  40 

- 

X 

oorm 

X 

X 

X 

X 

3  45 

•• 

X 

•■ 

X 

X 

X 

lovn 

9  47 

ii 

X 

- 

X 

X 

X 

n 

X 

953 

" 

X 

•• 

X 

X 

X 

X 

a 

Plate  E- 


—  Peport  for  Seasonal  Activities  of  Birds  — 


1 

1 

CS.. 

.So 

s 

c 
o 

I 

u 

Color   of  young 

Color  of  /duff 

J 

C3 

8 

O 

c 

5 

& 

Aj 

-* 

^ 

Robin 

Bluebird 

Chipping  5cmxj 

Gold  finch 

Cedar  Bird 

Bobolink 

Song  Sparrou 

Sandpiper 

Houx  Spanvu 

APPENDIX   B 

REGULATIONS    OF    THE    SANITARY    CODE 

ESTABLISHED    BY 

THE  PUBLIC  HEALTH  COUNCIL  OF  THE  STATE  OF 

NEW  YORK 

Condensed  from  the  Bulletin  of  the  New  York  State  Department  of  Health 

Isolation  of  Persons  Affected  with  Communicable  Diseases.  — 

It  shall  be  the  duty  of  every  physician,  immediately  upon  dis- 
covering a  case  of  communicable  disease,  to  secure  such  isola- 
tion of  the  patient  as  is  required  by  the  special  rules  issued 
by  the  local  health  authorities  or  by  the  state  department  of 
health. 

Adults  not  to  be  Quarantined  in  Certain  Cases. — When  a 
person  affected  with  a  communicable  disease  is  properly  iso- 
lated on  the  premises,  except  in  cases  of  smallpox,  adult  mem- 
bers of  the  family  or  household,  unless  forbidden  by  the  health 
officer,  may  continue  their  usual  vocations,  provided  such  vo- 
cations do  not  bring  them  in  close  contact  with  children. 

Removal  of  Cases  of  Communicable  Disease.  —  After  isolation 
by  the  local  health  officer  no  person,  without  permission  from 
him,  shall  remove,  or  permit  to  be  removed  from  any  room, 
building,  or  vessel,  any  person  affected  with  diphtheria,  scarlet 
fever,  smallpox,  or  typhus  fever. 

Without  permission  from  the  local  health  officer  no  person 
shall  remove,  or  permit  to  be  removed  from  any  dwelling,  any 
person  affected  with  chickenpox,  diphtheria,  epidemic  cerebro- 
spinal meningitis,  epidemic  or  septic  sore  throat,  measles, 
mumps,  poliomyelitis  (infantile  paralysis),  scarlet  fever,  small- 
pox, typhus  fever,  or  whooping  cough. 

408 


SANITARY   REGULATIONS  U 

Removal  of  Articles  Contaminated  with  Infective  Material. 
—  Without  permission  from  the  Local  health  officer  do  person 
shall  remove,  or  permit  to  be  removed  from  any  room,  build- 
ing, or  vessel,  any  article  which  has  been  Bubjecl  to  contami- 
nation with  infective  material  through  Asiatic  cholera,  diph- 
theria, scarlet  fever,  smallpox,  typhoid  fever,  or  typhus  I 
until  such  article  has  been  disinfected  according  to  the  special 
rules  and  regulations  of  the  3tate  department  "I  health. 

Exposure  of  Persons  Affected  with  Communicable  Disease. 
No    persons  shall   permil  any  child,   minor,   or  other  person 
under  his  charge,  affected  with   diphtheria,    measles,    scai 
lever,  smallpox,  or  typhus  fever,  i"  associate  with  others  than 
his  attendants. 

No  person  affected    with    any    of   -aid    diseases    -hall    e\p 

himself  in  such  manner  as  to  render  Liable  their  Bpread. 

Exclusion  from  School  of  Cases  of  Disease  presumably  Com 
municable.  —  It  shall  be  the  duty  of  the  principal  or  other 
person  in  charge  of  any  public,  private,  or  Sunday  school  to 
exclude  therefrom  any  child  or  other  person  affected  with  a 
disease  presumably  communicable  until  such  child  or  other 
person  shall  have  presented  a  certificate  issued  or  counter- 
signed by  the  health  officer,  stating  that  such  child  or  other 
person  is  not  liable  to  convex  infective  material. 

Exclusion  from  Schools  and  Gatherings  of  Children  of  House 
holds   where    Certain   Communicable    Diseases   Exist. —  Evi 
child  who  is  an  inmate  of  a  household   in   which  there  is,  oi 
has  been  within  fifteen  days,  a  case  of  chickenpox,  diphtheria 
epidemic  cerebrospinal  meningitis,  German   measles,  measl 
mumps,  poliomyelitis  (infantile  paralysis),  Bcarlel  fever,  small- 
pox, or  whooping  cmi-h.  shall  be  excluded  from  every  public, 
private,  or  Sunday  school   and   from  every   public  or  private 
gathering  of  children  tor  such  time  and  under  >uch  conditio 
as  may  be  prescribed  by  the  local  health  authorities. 

Precautions  to  he  observed  in  Chickenpox.  German  Measles. 
Mumps,  and  Whooping  Cough.  No  person  affected  with 
chickenpox,  German  measles,  mumps,  or  whooping  cough  shall 


410  APPENDIX   B 

be  permitted  to  come  in  contact  with  or  to  visit  any  child 
who  has  not  had  such  disease  or  any  child  in  attendance  at 
school. 

Isolation  or  Removal  in  Smallpox.  —  It  shall  be  the  duty  of 
every  health  officer,  whenever  a  case  of  smallpox  occurs  in  his 
jurisdiction,  if  a  suitable  hospital  is  available,  to  remove  or 
cause  to  be  removed  such  case  promptly  thereto.  Every  in- 
mate of  the  household  where  such  case  occurs,  and  every  per- 
son Avho  has  had  contact  with  such  case,  shall  be  either 
vaccinated  within  three  days  of  his  first  exposure  to  the  dis- 
ease or  placed  under  quarantine,  and,  when  vaccinated,  the 
name  and  address  of  such  inmate  or  other  person  shall  be 
taken  and  such  inmate  or  other  person  shall  be  kept  under 
daily  observation.  Such  observation  shall  continue  until  suc- 
cessful vaccination  results,  or  for  at  least  twenty  clays.  If 
such  inmate  or  other  person  refuses  to  be  vaccinated,  he  shall 
be  quarantined  until  discharged  by  the  local  health  officer. 

If  there  is  no  hospital  available,  the  patient  shall  be  isolated 
and  every  inmate  of  the  household  shall  be  vaccinated  or 
strictly  quarantined  until  discharged  by  the  local  health 
officer. 

Whenever  a  case  of  smallpox  occurs  in  his  jurisdiction,  it 
shall  be  the  duty  of  the  local  health  officer  to  use  all  diligence 
in  securing  the  names  and  addresses  of  all  persons  who  have 
had  contact  with  such  case,  and  in  causing  such  persons  to  be 
either  vaccinated  or  placed  under  quarantine. 

Maximum  Period  of  Incubation.  —  Tor  the  purpose  of  this 
code,  the  maximum  period  of  incubation  (that  is,  between  the 
date  of  the  exposure  to  disease  and  the  date  of  its  develop- 
ment), of  the  following  communicable  diseases  is  hereby  de- 
clared to  be  as  follows  : 

Chickenpox 21  days 

Measles 14  days 

Mumps 21  days 

Scarlet  fever 7  days 

Smallpox 20  days 

Whooping  cough 14  days 


SANITARY   REGULATIONS  -11  1 

Minimum  Period   of   Isolation.  —  The    minimum    period 
isolation,    within    fche    meaning    of    this    code,   Bhall    fc> 
follows : 

Chickenpox,  until  twelve  days  after  the  appearand  the 
eruption  and  until  fche  crusts  bave  Eallen  and  the  scan  are 
completely  healed. 

Diphtheria  i  membranous    CTOUp),  Until    two    BUCCe881ve    D( 

tive  cultures  have  been  obtained  from  fche  nose  and  throat  at 
intervals  of  twenty-four  hours. 

Measles,  until  ten  days  after  the  appearance  of  fche  rash  and 
until  all  discharges  from  the  nose,  ears  and  throat  hav< 
appeared  and  until  the  cough  has  erased. 

Mumps,  until  two  weeks  after  the  appearance  of  the  d 
and  one  week  after  fche  disappearance  of  the  Bwellin 

Scarlet  fever,  until  thirty  days  after  fche  development  of  fche 
disease  and  until  all  discharges  from  the  nose,  ears  and  threat. 
or  suppurating  glands  have  ceased. 

Smallpox,  until  fourteen  days  after  the  development  of  the 
disease  and  until  scabs  have  all  separated  and  fche  Bears  com- 
pletely healed. 

Whooping  cough,  until  eight  weeks  after  the  development  of 
the  disease  or  until  one  week  after  fche  last  characteristic 
cough. 

Sale  of  Food  Forbidden  in  Certain  Cases.  —  When  a  case  of 
diphtheria,  epidemic  or  septic  sore  Jjhroat,  amoebic  or  bacillary 
dysentery,  epidemic  cerebrospinal  meningitis,  scarlet  t«\ 
smallpox,  or  typhoid  fever  exists  on  any  farm  01  dair\  ] 
ducing  milk,  cream,  butter,  cheese,  or  other  foods  likely  t<>  be 
consumed  raw,  no  such  foods  shall  he  sold  or  delivered  from 
such  farm  or  dairy,  except  under  the  following  conditions  ■ 

(a)  That  such  foods  are  not  brought  into  fche  house  wh 
such  case  exists  ; 

(b)  That  all  persons  coming  in  contact  with  Buch  foods  eat, 
sleep  and  work  wholly  outside  such  hous< 

(c)  That  such  persons  do  not  come  in  contact  in  an\  way 
with  such  house  or  its  inmates  ox  contents  : 


412  APPENDIX  B 

(d)  That  said  inmates  are  properly  isolated  and  separated 
from  all  other  parts  of  said  farm  or  dairy,  and  efficiently  cared 
for  ;  and 

(e)  That  a  permit  be  issued  by  the  health  officer. 

Destruction  of  Foods  in  Certain  Cases.  —  When  a  case  of  diph- 
theria, epidemic  or  septic  sore  throat,  amoebic  or  bacillary 
dysentery,  epidemic  cerebrospinal  meningitis,  scarlet  fever, 
smallpox,  or  typhoid  fever  exists  on  any  farm  or  dairy  produc- 
ing milk,  cream,  butter,  cheese,  or  other  foods  likely  to  be 
consumed  raw,  the  state  commissioner  of  health  or  the  local 
health  officer  may  destroy  or  order  the  destruction  of  any  such 
foods  which  in  his  opinion  may  have  been  so  contaminated  as 
to  be  a  source  of  danger,  and  the  local  authorities  may  com- 
pensate the  owner  for  foods  so  destroyed. 

Handling  of  Food  Forbidden  in  Certain  Cases.  —  No  person 
affected  with  any  communicable  disease  shall  handle  food  or 
food  products  intended  for  sale,  which  are  likely  to  be  con- 
sumed raw,  or  liable  to  convey  infective  material. 

No  person  who  resides,  boards,  or  lodges  in  a  household 
where  he  comes  in  contact  with  any  person  affected  with 
bacillary  dysentery,  diphtheria,  epidemic  or  septic  sore  throat, 
measles,  scarlet  fever,  or  typhoid  fever,  shall  handle  food  or 
food  products  intended  for  sale. 

No  waiter,  waitress,  cook  or  other  employee  of  a  boarding 
house,  hotel,  restaurant,  or  other  place  where  food  is  served, 
who  is  affected  with  any  communicable  disease,  or  who  visits 
in  a  household  where  he  comes  in  contact  with  any  person  so 
affected,  shall  prepare,  serve,  or  handle  food  for  others  in  any 
manner  whatsoever. 

Cleansing,  Renovation  and  Disinfection  Required.  —  Ade- 
quate cleansing  of  rooms,  furniture  and  belongings,  when 
deemed  necessary  by  the  local  health  officer,  shall  immediately 
follow  the  recovery,  death,  or  removal  of  a  person  affected 
with  a  communicable  disease.  Such  cleansing  shall  be  per- 
formed by  or  at  the  expense  of  the  occupant  of  said  premises, 
under  the  direction  of  the  local  health  officer. 


SANITARY   REGULATIONS  413 

Adequate  renovation  of   premises,  when   <lf.-in.Mi  n..-. 
by  the  local  health  officer,  sh.-ill  immediately  follow  the  i 
ery,  death,  or  removal  of  a  person  affected  with  a  communi 
disease.     Such  renovation  shall  be  performed  by  and  at   the 
expense  of  the  owner  of  said  premises  or  his  agents  under  the 
direction  of  the  local  health  officer. 

Adequate  disinfection  of  premises,  furniture  and  belongin 
when  deemed  necessary  by  the  h><-al  health  officer,    shall   im- 
mediately follow  the  recovery,  death,  or  removal  of  a  \  ■• 
affected  with  a  communicable  disease     Such  disinfection  Bha  1 
be  performed  by  or   under  the  direction  of   the  local  health 
officer  in  accordance  with  the  regulations  of  the  Banitary  o 
and  at  the  public  expense  unless  otherwise  pursuant  to  law. 


APPENDIX   C 

"WHAT   PEOPLE   SHOULD   KNOW  ABOUT    CANCER 

Francis  Carter  Wood,  M.D. 

Condensed  from  the  Bulletin  of  the  New  York  State  Department  of  Health. 

Cancer  not  a  Germ  Disease.  —  The  cause  of  cancer  is  still 
unknown,  but  this  does  not  prevent  our  being  able  to  cure  it. 
The  disease  is  quite  unlike  those  due  to  germs,  of  which  so 
much  has  been  learned  in  the  last  thirty  years,  and  no  germ 
which  is  capable  of  causing  cancer  in  human  beings  or  in  ani- 
mals has  been  found.  Cancer  is,  therefore,  not  contagious,  and 
there  is  no  danger  in  treating  or  in  dressing  a  cancer  case. 
Ordinary  cleanliness,  however,  requires  that  the  soiled  dress- 
ings shall  be  burned  —  not  because  there  is  any  danger  of 
contagion  of  cancer,  but  because  the  discharges  and  dressings 
contain  germs  such  as  those  which  cause  boils,  erysipelas,  and 
other  skin  inflammations. 

Cancer  not  Contagious.  —  As  cancer  is  not  contagious  there 
is  no  reason  to  believe  the  stories,  so  often  told,  of  "  cancer 
houses,"  or  "  cancer  villages  "  or  "  cancer  belts."  The  occur- 
rence of  a  large  number  of  cases  of  cancer  in  a  house  can 
usually  be  shown  to  be  due  to  the  fact  that  the  house  has  been 
occupied  by  old  people.  Since  cancer  is  a  disease  of  old  age 
there  will  naturally  be  more  cases  of  the  disease  in  such  a 
house  than  in  one  which  has  been  occupied  by  a  number  of 
young  people. 

Cancer  not  Hereditary.  —  Cancer  is  not  hereditary,  although 
much  has  been  said  and  written  about  certain  experiments  with 
strains  of  white  mice  to  show  that,  by  inbreeding,  the  occur- 
rence of  cancer  in  these  animals  is  much  increased.     While 

414 


CAXCER  11.") 

there  is  no  question  that  tins  is  a  fact,  yel  the  increase  can  be 
obtained  only  in  certain  strains  of  white  mice,  not  in  all  varie- 
ties, and  lias  never  been  observed  in  white  rat  tinea 
rabbits,  dogs,  or  other  animals  in  which  cancer  occurs.  There- 
fore, there  is  no  reason  to  worry  because  one  member  of  your 
family  has  suffered  from  cancer.  It  does  no1  at  all  follow  that 
any  other  member  of  the  family  will  have  it.  In  a  family  the 
members  of  which  tend  to  be  very  long-lived,  more  cases  of 
cancer  will  occur  than  in  one  in  which  the  members  die  young, 
but  this  is  not  because  can  err  is  hereditary. 

Cancer  Attacks  the  Healthy.  —  CTnfortunately,  cancer  attacks 
not  only  those  who  are  in  feeble  health,  but  also,  and  with 
equal  frequency,  those  who  are  strong  ami  healthy  ami  h. 
never  suffered  from  any  other  disease.  For  tin-  reason,  it  is 
especially  important  that  such  healthy  people  Bhould  consult 
a  physician  if  any  sudden  change  in  their  well-being  tak 
place,  and  particularly  if  there  is  any  digestive  disturbance  or 
disorder  of  the  bowels,  for  the  stomach  and  intestines  are  fre- 
quent sites  of  cancer. 

AVe  see,  therefore,  the  unfortunate  circumstances  that  while 
the  improvement  in  conditions  of  living  has  prolonged  the  lite 
of  the  community  on  an  average  of  ten  years  in  the  last  cen- 
tury, the  same  condition  has  apparently  increased  the  number 
of  cases  of  cancer,  since  there  are  more  people  who  reach  the 
cancer  age  than  formerly.  This  gives  more  cases  of  cancer  in 
the  population  as  a  whole,  though  the  relative  proportion  per 
age  group  may  not  be  increased. 

How  Cancer  Begins.  —  While,  as  has  been  Baid,  we  do  not 

know  the  cause  of  cancer,  we  do  know  a  g 1  deal  about  how 

it  occurs  and  what  is  apt  to  precede  it.  For  instance,  cancer 
frequently  begins  in  moles  or  warts  which  are  irritated  by  the 
clothes  or  are  made  to  bleed  and  are  kept  Bore  by  repeated 
injury  of  any  sort.  Such  warts  and  moles  are  perfectly  harm- 
less at  first,  and  become  dangerous  only  after  thej  have  been 
irritated  in  this  way  tor  a  long  time,  especially  if  the  person 
is  of  the  cancer  age,  that  is,  above  forty-five  yeai        It  1-  \\ 


416  APPENDIX   C 

therefore,  to  have  such  moles  removed  if  they  are  in  a  situation 
where  they  are  liable  to  be  rubbed  or  injured.  It  has  been 
found,  also,  that  cancer  frequently  develops  in  the  scar  of  an 
old  burn,  or  in  places  where  there  is  a  chronic  ulcer,  as  on  the 
lip  or  tongue  or  leg,  and  care  should  be  taken  to  see  that  such 
ulcers  are  healed  as  quickly  as  possible. 

Ulcers  on  the  tongue  and  cheek  frequently  follow  scratching 
from  a  poor  filling  or  from  the  sharp  point  of  a  decayed  tooth, 
and  a  dentist  should  be  consulted  if  such  an  ulcer  does  not 
heal  within  a  few  days,  so  that  the  filling  may  be  properly 
replaced  or  the  point  of  the  tooth  hied  off.  Smokers  should 
be  particularly  careful  about  any  sore  on  the  lip  or  tongue ; 
these  are  commonly  found  in  those  who  use  a  pipe  or  cigars 
and  smoke  so  that  the  tissue  is  burned  by  the  hot  stem  of  the 
pipe  or  at  the  point  where  the  hot  cigar  smoke  strikes,  thus 
keeping  up  a  chronic  irritation.  For  this  reason,  cancer  of 
the  lip  and  tongue,  while  very  common  in  men,  is  almost  never 
seen  in  women. 

The  beginning  of  an  internal  cancer  is  much  more  difficult  to 
determine,  because  small  tumors  just  as  they  start  cannot  be 
discovered  except  by  accident ;  but  it  has  been  found  that  they 
almost  always  begin  in  some  injury  ;  for  instance,  ulcer  of  the 
stomach  is  a  common  cause  of  cancer,  since  the  ulcers  turn  into 
cancers  if  they  are  not  cured  by  proper  medical  or  surgical 
treatment.  So,  too,  cancers  of  the  lower  bowel  are  frequently 
preceded  by  chronic  inflammation,  and  persons  suffering  from 
chronic  dysentery,  ulceration  of  the  bowel,  or  bleeding  piles, 
should  consult  a  physician  to  see  that  these  troubles  are  cured 
promptly  and  do  not  develop  into  cancer. 

Cancer  of  the  breast  in  women  frequently  follows  chronic 
inflammation,  and  is  not  caused  by  a  blow,  as  is  frequently 
thought.  Any  woman  who  notices  a  lump  in  the  breast  should 
at  once  consult  a  physician.  It  is  very  much  better  to  be  told 
that  the  thing  is  harmless  and  need  not  be  removed,  than  to 
wait  too  long,  only  to  find  that  it  has  already  developed  into  a 
cancer. 


CANCEL'  417 

Nature  of  Cancer.  —  Cancel  is  a  \.t\  curious  di  •  which 
is  due  to  the  running  awaj  of  certain  parts  of  the  bodj  tissue, 
that  is,  a  few  cells  in  the  breast  or  in  the  liver  or  in  anj  other 
organ  grow  beyond  the  natural  limit  and  invade  the  Burroundi 
tissues;  then  we  have  a  cancer.  This  cancer  often  d  •  cot 
give  any  notice  of  its   presence   until  a  1  < •  1 1 .^r  time  r  the 

trouble  has  started,  because  the  cells  composing  it  are  the  Bame 
(or  nearly  the  same)  as  the  cells  from  which  they  Btarted, and, 
therefore,  the  body  dot-s  nol  recognize  the  Eacl  thai  a  cancer  is 
growing  until  it  becomes  of  considerable  Bize.     It  Btarts  very 
quietly,  is  very  small  at  first,  but  gradually  grows  and  destn 
the  very  tissues  that  1'rrd   it,  until  ultimately  it    kills  its  fa 
by  injuring  some  important  part  of  the  body.      I'-nt   it    is,  in 
such  a  case,  the  cells  of  the  body  itself  which  are  the  parasifr 
in  other  words,  there  is  no  parasite  introduced  from  the  outside 
to  cause  the  cancer. 

•  Kinds  of  Cancers.  —  There  are  many  kinds  of  cancer,  and 
each  kind  acts  differently  and  spreads  in  it >  own  way  through 
the  body.  Certain  forms  which  arise  in  glands,  such  as  the 
breast,  are  called  carcinoma,  and  this  sort  spreads  slowly  t«» 
places  where  there  are  small  nodules  of  tis>ue>.  called  lymph 
nodes,  in  which  the  cancer  collects,  forming  there  Beoondary 
lumps  or  metastases,  as  the  physician  calls  them.  The  true 
carcinoma  does  not  often  get  into  the  blood  vessels,  and  there- 
fore it  remains  localized  for  a  very  considerable  time,  bo  that 
the  surgeon  has  an  opportunity  to  remove  it,  it'  the  diagnoc 
is  made. 

Another    kind    of    cancer,    called    by    physicians  •<-', 

spreads  to  the  blood  vessels  and   consequently    is   much   ni' 
difficult  to  cure,  because  this  spreading  takes  place  v.  i\  early 

in  the  course  of  the  disease  and  the  cells  arc  BWepf  all  0\  er  the 

body,  starting  new  little  tumors  where  fchej    are  deposited. 

While  cancer  grows  through   the  very  t:  which  surround 

it,  it  does  not  have  roots,  as  the  quacks  Bay.  W  hat  are  called 
roots  are  more  frequently  blond  vessels  leading  from  the  oan- 
cer,  or  bits  of  fibrous  tissue;  so  that  when  a  quaes 


418  APPENDIX   C 

patient  that  he  takes  a  cancer  out  "  by  the  roots,"  he  is  talking 
nonsense. 

Some  cancers  grow  very  slowly ;  for  instance,  some  of  those 
on  the  skin  may  remain  for  ten  or  twenty  years  without 
spreading  any  very  great  distance  and  without  forming  little 
lumps  elsewhere  in  the  body.  Other  cancers  grow  very  rap- 
idly and  are  fatal  within  a  few  months.  Most  cancers,  however, 
remain  local  for  a  considerable  period,  probably  six  months  to 
two  years,  before  they  really  start  to  spread  out  in  the  tissues 
and  if  only  they  can  be  discovered  and  cut  out  during  an  early 
stage,  the  patient  can  be  surely  cured. 

Symptoms  of  Cancer.  ■ —  Unfortunately,  the  very  smallest 
cancers  give  no  symptoms  unless  they  are  on  the  skin  or  lip  or 
tongue  or  elsewhere  on  the  surface  of  the  body ;  and  in  these 
situations  the  earliest  diagnosis  can  be  made.  Cancers  the  size 
of  a  pea  or  but  little  larger  are  often  diagnosed  and  removed 
by  a  surgeon  with  an  assured  result,  if  the  operation  has  been 
properly  done. 

In  the  stomach  and  internal  organs,  however,  the  cancer 
does  not  give  rise  to  symptoms  until  it  is  quite  large,  and  it  is 
important,  therefore,  for  anyone  who  has  any  disturbance  of 
the  stomach  or  intestines,  loss  of  weight,  or  anemia,  to  go  at 
once  to  a  surgeon,  because  by  modern  chemical  methods  and 
by  the  use  of  the  X-ray  a  diagnosis  can  often  be  made  on  one 
of  these  cancers  long  before  it  can  be  felt  or  seen. 

One  of  the  last  symptoms  of  cancer  is  pain  ;  this  is  due  to 
the  pressure  on  the  nerves  by  the  growth  spreading  out  through 
the  tissues.  When  a  cancer  gives  a  great  deal  of  pain  it  is 
usually  beyond  operation.  Bleeding  is  a  common  result  of 
cancer  of  the  intestines,  and  is  one  of  the  most  important 
symptoms.  Every  one  should  know,  however,  that  when  a 
lump  appears  anywhere  on  the  body,  a  physician  should  be  seen 
immediately ;  the  lump  may  prove  to  be  an  abscess  or  some- 
thing quite  harmless,  for  there  are  a  good  many  tumors  which 
are  quite  harmless,  or  it  may  prove  to  be  a  cancer,  and  then  if 
it  has  been  seen  early  enough,  it  can  be  cured  by  operation. 


CAM  EH  \\\\ 

Occurrence  of  Cancer.     -  It  has  been  Bhown  l»v  the  Btudv  of  a 
large  number  of  cases  of  cancer  in  various  countries,  thai  the 
disease  afflicts  chiefly  those  of  middle  age,  thai  is,  from  fori 
five  to  sixty-five  years.     Younger  people  and  tho  r  eighty 

years  are  rarely  afflicted  with  cancer,  excepl  thai  in  very  old 
people  various  mild  cancel's  of  the  skin  are  no1  infrequent; 
these,  however,  are  easily  cured  by  the  X-ray  or  radium,  and 
do  not  need  operation  in  all  cases. 

Women  about  the  age  of  forty-five  to  fifty-five  Bhould  b< 
careful,  if  any  lump  appears  in  the  breast,  to  have  a  careful 
examination   made.     Men  of   aboul   this  age,  also,  should   be 
watchful  of  ulcers  on  the  lip,  tongue,  or  inside  of  the  che< 
especially  if  the  teeth  are  not  good,  and  should  have  any  Buch 
ulcers  immediately  examined  by  a  physician.     The  physician 
may  have  to  cut  out  a  small  piece  and  send  it  to  a  laboratory 
in  order  to  determine  whether  or  not  the  growth  is  cancerous, 
if  it  is  too  small  to  diagnose  otherwise.     It  is  very  much  betl 
to  have  a  diagnosis  made  early  than  to  wait  until  the  doctoi 
sure  that  the  thing  is  a  cancer,  for  it  is  then   often  beyond 
operation. 

Treatment  of  Cancer.  —  The  proper  treatmenl  of  cancer  i^ 
the  removal  of  the  growth  as  early  as  possible,  it  being  re- 
membered always  that  cancer  is  a  local  disease  when  it  begins 
and  as  a  rule  spreads  through  the  tissues  only  after  a  consid- 
erable time.  The  removal  of  small  cancers  or  of  beginning 
cancers  is  often  an  easy  matter  and  can  be  done  under  cocaine. 
Internal  cancers,  of  course,  can  be  removed  only  by  an  exten- 
sive operation;  but  the  methods  now  are  so  successful  thai  a 
very  large  proportion  of  the  eases  can  be  saved  it  operation 
done  early. 

There  is  a  popular  impression  thai  cancer  is  incurable. 
This  is  not  so.  Early  operation  cures  Borne  kinds  of  can. 
for  instance  those  of  the  lip,  in  about  96  per  cut  of  the  casi  - 
operated  upon.  If  cancer  of  breast  also  could  he  operated  upon 
at  an  early  stage,  nearly  tour  fifths  of  the  cases  would  remain 
well.     When  operated  upon  at   a   late  Btage,  onlj    one  fifth 


420  APPENDIX  C 

the  cases  are  cured,  that  is,  show  no  further  appearance  of  the 
tumor. 

Eadium  and  X-rays  are  very  good  treatment  for  the  small 
cancers  which  appear  on  the  faces  of  old  people,  and  in  some 
cases  may  be  very  useful  in  helping  to  complete  the  surgical 
cure  by  healing  any  small  lump  which  appears  after  operation. 
They  are  also  the  best  treatment  for  a  cancer  which  has  gone 
so  far  that  it  cannot  be  operated  upon,  and  in  such  a  condition 
may  frequently  be  of  such  benefit  that  the  patient  may  live  a 
couple  of  years  in  comfort,  but  as  a  rule  they  do  not  cure  can- 
cer, and  they  should,  therefore,  never  be  used  on  a  cancer  of 
any  size ;  instead,  such  a  tumor  should  always  be  operated 
upon. 

Great  care  should  be  taken  in  selecting  a  physician  to  give 
the  treatment  with  X-rays  or  radium,  because  only  a  few  per- 
sons have  enough  radium  for  proper  treatment,  and  only  a  few 
doctors  know  how  Jo  administer  without  burning  the  patient 
seriously,  the  large  quantities  of  X-rays  which  are  necessary  to 
produce  good  effects.  It  is  better  that  a  patient  should  go  to 
a  hospital  and  get  suitable  treatment  there,  rather  than  to  let 
his  local  physician  experiment. 

The  use  of  salve  and  other  forms  of  treatment  which  are 
widely  advertised  in  the  newspapers  are  worse  than  useless. 
They  often  stimulate  the  cancers  and  make  them  grow  more 
rapidly  ;  or  if  they  do  eat  off  the  top  of  the  growth,  they  leave 
the  bottom  spreading  in  deeply,  and  what  is  worse,  result  in 
a  waste  of  time,  for  the  tumor  should  be  operated  upon 
promptly. 

Xo  form  of  internal  medicine  will  cure  a  cancer ;  that  we 
know  absolutely.  Xor  will  any  fluid  injected  under  the  skin 
cure  a  cancer.  Cases  of  cures  by  such  means  which  are  re- 
ported in  the  papers  or  are  talked  about  are  merely  instances  of 
mistaken  diagnosis,  for  the  quack  relies  upon  the  ignorance  of 
people  as  to  what  a  cancer  is  and  what  it  is  not.  Any  small 
lump  is  called  a  cancer  by  the  quack ;  then  if  it  disappears  he 
will  say  he  has  cured  it.     As  a  matter  of  fact,  a  great  many 


CANCER  l_'l 

tests  have  been  made  of  Hit-  <;i  m««t  cures  which  are  Bold  in  this 
country,  and  none  of  them  have  been  found  to  be  of  the  slight- 
est value  in  the  treatment  of  real  cancer,  and  real  cancer  is  the 
thing  in  which  people  arc  deeply  interested,  because  through 

it  their  lives  are  in  danger. 


[NDEX 


U>  /<  r<  net  s  art  to  /"■•■ 


Abdomen,  of  crayfish  .    .    .    .  86 

of  grasshopper 13 

Abnormal  growth  of  tissue 

cause  of  disease  ....  233 

Abomasum.  division  of  Btom- 

ach  of  sheep  (ti^.)    ....  154 

Absorption,  of  food,  defined  17.'! 

of  food  not  nourishment   .  l T ~» 

Absorption  in  leaves  of  Ve- 

nus's  fly-trap 39] 

Abstainers'    record  in  -walk- 
ing- match  (fig.)      ....  224 

Acid  secreted  by  roothairs     .     .  269 

Acid  medium  in  stomach  .     .  171 

Aconite,  a  poison 221 

source  of 327 

Acorn,  a  dry  fruit  (fig.)     .     .     .  309 

Actinozoa,  example  of      ...  <> 

Active  bacteria   reduced  in 

number  by  heating  milk  Ml 

Adam's  apple 193 

Adaptation,  defined      ....  161 

student  report  on 162 

Adaptations,  of  birds  .     .     .     .  138 

of  reptiles 1  •">! 

Adductor  muscles  of   clam 

(figO    •     •     •         95 

Adulteration  of  foods    .     .     .  180 

Adventitious  roots     .     .     .     .  284 

experiments  to  show    .    .    .    .  404 

Aerial  roots,  of  corn    ....  280 

of  ivy  (fig.) 284 

Aerial  stems 286 

Afferent  fibers 213 

Agar-agar,  formula      ....  346 
plates  (fig.)     •    •     348,349,360,351 
Agave,     section    of    epidermis 

(fig-) 8« 


Age  of  trees,  how  *.ld 
Agencies    of    seed    distribu- 
tion          312 

Agriculture,  amount  and  kind 

of  cultivation  in 

as  an  industry 

influence  of  mi  civilization  . 
Air.  home  of  bacteria     .    ...    344 

Air  cells  of  lung 

Airspaces  in  stems,  function 

of 

Albumen,  examples  of      .     .     .     176 
Alcohol,  ambitioD  destroyed  b 

a  narcotic 221 

;i  poison 221 

and  disease 243 

and  patent  medicines  .... 

canst-  (if  disease 

chemical  composit  ion  "f .     .         I7»'i 
effect  of.  on  circulation   .... 

<>n  digestion 182 

formed  by  yeast  plant  .  .  . 
in  bread  driven  off  by  beat  ,  . 
Protozoa  and 

vliorteii~.  life 221 

use  of  in  consumption 
Alcoholism  a  disease      ... 
Ale.  manufacture  of 
Alfalfa,  member  "f  pulse  famil 

rooi  (fig.) 

Algae,  aquatic  plants 

example  of 7 

lark  ..I  conduct!]  tern  in    . 

number  of 7 

Alimentary    canal,    of    fp 

(fig.) 117. 

of  man  (ti-   | 161 

Alkaline  medium  in  mouth    .     171 
Alligator  <  l i ^ -  > 

nest  


1 


INDEX 


References  are  to  pages 


Alligators,  classified    ....  7 

described 133 

example  of  reptiles      ....  129 
Alternate    leaves,    of    beech 

family 327 

of  nightshade  family   ....  331 

of  parsley  family 329 

of  pulse  family 329 

of  rose  family 328 

of  walnut  family 327 

Alternation  of  generations, 

in  coelenterates 68 

in  ferns 372 

in  mosses 366 

Althaea,     member    of    mallow 

family 329 

Altricial  birds,  defined    .     .     .  142 

nest  of  yellow  warbler  (fig.)     .  142 
American  elm,  scientific  name 

of ^ .     .  7 

Ammonia  in  test  for  protein  265 
Ammonium  tartrate  in  Pas- 
teur solution 356 

Amoeba,  classified 6 

described 47 

diagram  of  (fig.) 48 

microphotograph  of  (fig.)     .     .  47 

reproducing  by  fission  (fig.)     .  49 

reproduction  of 3 

respiration  of 49 

Amphibians,  described     ...  113 

economic  importance  of  .     .     .  127 

example  of 7 

laboratory  study  of     ....  113 

number  of 7 

summary  of 127 

Amphioxus,  notochord  of     .     .  104 

Anatomy  of  starfish  (fig.)  .     .  72 

Anesthetic,  defined      ....  221 

dissolves  lipoid 223 

Angiosperms,  classes  of  .     .     .  7 

defined 7 

Animal  biology 11 

Animal  cell  (fig.) 4 

Animal  parasites,  habits  of     .  233 

Animal  starch,  in  liver   .     .     .  174 
Animals,  agents  in  distribution 

of  seeds 313 

decomposed  by  bacteria  .     .     .  345 

without  a  backbone     ....  6 


Annelida,  a  class  of  worms  .     .  76 
Annual  rings,  age  of  tree  told 

by 377 

in      longitudinal     sections     of 

trunks 291 

in  stem  of  pine 377 

Anopheles,  mosquito  (fig.)   .     .  42 

cause  of  malaria      .     .     .     .42,  238 

Antennae  of  grasshopper  .     .  14 
Anterior  adductor  muscle  of 

clam 95 

Antheridia  of  fern 371 

of  moss 365 

Antheridial    plant    of    mar- 

chantia  (fig.) 365 

Anthers,  described 296 

Anti-pain  medicines  ....  246 

Antitoxin,  defined 351 

described 252 

in  preventing  spread  of  disease  246 

use  of  in  diphtheria     ....  253 
Ants,  example  of  complete  met- 
amorphosis    19 

social  life  of 41 

Anus,  in  digestive  system  of  man  169 

Aorta,  largest  artery  in  man      .  202 

Aortic  arches  of  earth-worm  82 

Aphis,  woolly  (fig.) 25 

Apiary,  escape  of  bees  from  .     .  35 

model  (fig.) 38 

Appendicitis 168 

Appendix,  vermiform  ....  168 

X-ray  photograph  of  (fig.)    .     .  169 
Appetite,  guide  to  amount  of 

food 180 

Apples,  a  form  of  fruit      .     .     .  310 

example  of  pome  (fig.)     .      309,  310 

produced  by  rose  family  .     .     .  329 

value  of  as  food 178 

Aqueous  humor 216 

Arachnids,  list  of 91 

Arbor  vitae,  cones  of  (fig.)    .     .  378 

Arch,  of  foot 187 

of  hypocotyl  of  bean    ....  264 

Archegonia,  of  fern      ....  371 

of  moss 365 

Archegonial   plant    of    mar- 

chantia  (fig.) 365 

Arctic  regions,  adaptations  for  161 

plants  of 396 


INDEX 


Reft  r>  run  i 

Arctic  regions,  continued 

plants  of ,  modifications  of    .    .  397 

use  of  lichens  in 361 

Arm,  superficial  lymphatics  <>f 

(fig.) 304 

Arms,  example  of  organ    ...  B 

of  starfish "_' 

Army  worm,  harmful  insect  28 

Arsenic,  a  poison 232 

Arteries,  function  of    .    .    .  L97,  201 

in  circulation  of  clam  ....  (.»7 

of  crayfish 90 

of  fishes 109 

<ff  man 201 

Arthropoda,  classified      ...  <» 

example  of 6 

number  of <> 

word  explained 86 

Arthropods.  Bummary  of     .     .  93 

Artificial  respiration .     .     .     .  VX> 

Aseptic,  defined 347 

Asexual      reproduction,      of 

amoeba 3 

of  coelenterates <><> 

Ash,  result  of  chemical  change  .  9 

Ash  twig  (fig.) 289 

Asparagus  beetles      ....  26 

Assaults  and  drink  (fig.)     .     .  222 

Assimilation,  defined  ....  2 

in  plants 279 

Aster,  a  common  weed  ....  3.'i4 
Atmosphere,  composition  of    ,  '-1 
Auditory  organ  of  grasshop- 
per        16 

Auricles  of  heart 201 

B 

Bacillus,  a  form  of  bacteria  .     .  343 
Bacillus   tuberculosis,    cause 

of  consumption 235 

Bacteria,  action  on  lava    .     .     .  4<x> 

and  mold  from  bouse  tly  (fig.)  ■  251 

carried  by  insects 315 

cause  of  sour  bread      .     .     .     •  179 

classified 1 

conditions  necessary  forgrowth  344 

decomposition  of  materials  by  ■  '>}! 

discussed     

distributed  by  (lies ;;*7 


art  to  /""/■ 

Bacteria,  continut  <t 
etTect  ni  on  medium  on  which 

they  gro* 

fonns  ol  (fig.) 

harm  to  teeth  from  p. 7 

harmful 

helpful 

important  plants     .... 

in  formation  of  Soil       .  J"1 

injury  caused  to  bean  plant  bj 

in  relation  to  milk 

in  runts  of  beans  ....     270, 

in  warm  milk 

laboratory  b1  ody  of     .... 

life  processes  of 

multiplication  of 

proper  conditions  for  growth  of 
shape  and  size 

corkscrew  (spirilla) .... 

rod-shaped  (bacilli)  .... 

round  (cocci) 

Soil      (fig.) 

Bource  of  disease 4"1 

summary  of    .     .  .... 

unfavorable    conditions    with- 
stood by 346 

where  found 341 

Bacterial    growths   on   agar 

plates  (fig.) 

Bacterial  poison,  toxin    ,     .     . 
Bailer    in    gill    chambers    of 

crayfish      

Balanced  ration 177 

Balancing,  use  of  tins  for       .     .      P>7 
Balancing  organ.  .;ir  a    ■  .     218 

Balaam,  adventitious  roots  on        i"i 

Balsams,  conifers 

Bananas,  value  of  M  fond  17s 

Barberry  leaves  i  tiir  i      ... 

Bark,  function  of 

Barley,  n  cereal  (figO    ■     •     •     • 

;t  monocotj  ledon      .... 

member  of  the  grass  family 

0D6    Of    the    tirst    plants    culti- 
vated     

source  of  liquors      .... 
Barnacles,     economic     Impor- 
tance of  (fig.) "i.  i"1 

Baseball,  advantage  of  M  i  nt- 

eise 


INDEX 


References  are  to  pages 


Bass,  a  bony  fish 106 

example  of  fish 6 

Bat,  enemy  of  mosquito      ...  42 

hibernating  (fig-) 151 

Beaks  of  birds,  variations  in    .  137 

Bean,  an  irregular  flower  .     .     .  302 

distribution  of 318 

early  cultivation  in  America    .  317 

embryo,  growth  of 264 

example  of  dicotyledons  ...  7 

field  (fig.) 317 

flower  (fig.) 296 

foodstuffs  in 265 

fruit  of  (fig.) 307 

germination  of  (fig)    ....  264 

leaf,  cross  section  of  (fig)    •     .  273 

pistil  (fig.) 297 

plant  (fig.) 259,  267 

injured  by  bacteria  (fig.)  .     .  315 

reasons  for  studying     .     .     .  259 

raising  of 316 

root,  central  cylinder  of  (fig.)  .  268 

cortex  of  (fig.) 268 

epidermis  of  (fig.)     ....  268 

sections  of  (fig.) 268 

showing  tubercles  (fig)     •     •  270 

seed,  laboratory  study  of     .     .  261 

parts  of  (fig.) 260 

relation  to  flower      ....  297 

seedling,  parts  of 267 

stamen  (fig.) 297 

stem,  laboratory  study  of     .     .  272 

summary  of 320 

Bean  and  pea,  photographs  of 

(fig.) 260 

Bean  blight 315 

Bean  family,  members  of      .     .  318 

Bean  -weevil,  larvae  of      .     .     .  316 

work  of 315 

Beans  as  food 178 

cheapness  of,   compared    with 

meat 317 

digestible •     .     .  317 

for  hogs  or  sheep 316 

value  of 317 

Beans  damaged   by  -weevils 

(fig.) 315 

Bee     farms,     escape     of    bees 

from 35 

Bee  fly,  a  beneficial  insect     .     .  41 


Beech,  value  of 

Beech  family,  description  of  . 
Beech    leaves,    and    buds    of 

(fig-) 

Beechnut,  a  dry  fruit  (fig.)  .  . 
Beef,  value  of,  as  food  .... 
Beef  extract,  in  agar-agar  .  . 
Beef  jelly  exposed,  in  sanitary 
dairy  (fig.) 

in  unsanitary  dairy  (fig.)  .  . 
Beer,  manufacture  of    ...     . 

use  of  yeast  in  making  .  .  . 
Bees,  capturing  a  swarm  of  (fig.) 

classes  of    

classified  insecta 

clustering    at    swarming   time 

(fig-) 

complete  metamorphosis  of  .     . 

cutting  comb  from  hive  (fig.)    . 

drone      

gathering  of  nectar  by     .     .     . 

honey,  value  of 

imperfect  female  (worker)   .     . 

members  of  Hymenoptera    .     . 

nurses 

perfect  female  (queen)     .     .     . 

swarming 

wax,  value  of 

Beet,  a  dicotyledon 

roots  of  (fig.) 

storage  of  food  in 

Beetle,  May,  a  harmful  insect   . 

potato,  a  harmful  insect  .  .  . 
Beetles,  classified 

example  of  complete  metamor- 
phosis   

field  study  of 

Belladonna,  compared  with 
stramonium 

source  of 

Berries,  produced  by  rose  family 
Berry,  a  form  of  fruit  .... 

collection  of  drupes     .... 

defined 

illustration  of  (fig.)     .... 

pepo,  special  kind  of  ...  . 
Bichloride  of  mercury,  use  of 
Bilabiate  flowers  of  mint  .  . 
Bile,  a  digestive  juice  .... 
Biological  diseases,  kinds  of  . 


327 
327 

327 
309 
178 
346 

350 

351 

355 

354 

37 

f  35 

6 

36 

19 

39 

35 

297 

39 

35 

20 

36 

35 

37 

39 

263 

283 

283 

26 

26 

20 

19 
12 

331 
331 
329 
308 
310 
310 
310 
311 
253 
331 
172 
233 


i  \  Di:\ 


Referenc*  a  ><>■■  to  pa 


Biology,  defined 1 

of  disease 232 

Birch    roots,     photograph     ol 

(fig.) 392 

Bird  house,  plan  for  (fig.)    .    .  lis 

Birds,  characteristics  of     .    .    .  L36 

classified 7 

economic  importance  of  .     .     .  Ill 

number  of 7 

summary  of 149 

Birds'  feet,  different  kinds  of 

(rig.) 139 

Bitter,  a  fundamental  taste  .     .  165 

Bittern,  beak  of 137 

nest  of 14'J 

Bivalves,  reason  for  name     .     .  98 

Blackberry,  in  plant  succession  4(H) 

receptacle  of  fruit  eaten  .     . 


Blackbirds,  food  of 


31, 


310 

14.") 
132 
207 


294 
257 
197 


Black  snake,  a  constrictor    . 

Bladder   

Blade  of  bean  leaf     .     .     . 

of  leaf,  food  storage  in  .  . 
Blind  persons,  number  of  . 
Blood,  corpuscles      .... 

of  man 197 

plasma 197 

student  report  on '200 

vessels,  function  of      ....  :'. 

Bluebird,  a  beneficial  bird    .     .  144 

destroyed  by  hawks     ....  145 

destroyer  of  Lepidopt era      .     .  31 

food  of '-"J 

Blue   jay,  at  bread  crumb  sta- 
tion       14S 

at  suet  station 148 

at  whole  grain  station      .     .     .  14'.i 

feeds  on  larva;  of  Lepidqptera  31 

Blue  racer,  a  constrictor  .     .     .  132 

Boa-constrictor 132 

Boards  of  health 246 

Bobolink,  female  (tig.)      ...  1  16 

food  of 11" 

migratory  habits  of          .     .     .  143 

nesting  habits  of in 

Body,  parts  of I 

Body  cavity  of  earthworm   .  81 

Body  temperature,  of  birds    .  138 

of  mammals 150 

of  man 190 


Bone,  microphotograpb  of  (flg.) 

Bt  rucl  ure  of  ( t\g  i 

Bony  fishes,  list  of 

Borax,  a  preservative  .... 
Borers,  harmful  beetles    .    .    . 

eaten  by  downy  \\  oodpecker 
Boric  acid,  a  preservative 
Botfly,  harmful  Insect  .... 
Bottling-,  good  and  bad  (fig  I 
Bougainvillea  hydroid  [fig 
Bracket  fung-i,  ctT.-ct  on  trees 
Bracket  fung-us  (tiur)  .     .     .     . 
Brain,  conl  rol  (fig.) 

efficiency,  discussion  of  .    .    . 
conditions  Decessarj  for  .    . 

microphotograpb  of  ( fig  > 
"  Brain  "  of  earthworm      .     . 

Braincase 

Bran,  used  as  an  adulterant  .      . 

Branch,  example  of  organ 

Branch    infected    with    mis- 
tletoe (fig.) 

Bread,  crumbs  for  feeding  station 

mold  (  fig. )       

laboratory  study  of .    .    . 
rye,  \  alue  of  as  food    .... 
use  of  yeast  in  making 

wheat ,  value  id  as  food    . 
Bread-making,  scientific  Ka^is 
of 

temporary  by-products  of    .    . 
Breathing,  in  grasshopper    .     . 

in  man 

not  respiration 

Breathing  center  in  develop- 
ing embryo  

Brewing,  scientific  basis  of  .     . 

Bronchus     

Brook  trout  (  i'il:  > 

raised  in  hatcheries     .... 

Brown  bat  (fig.) 

Brown     creeper,     at      bread 
crumb  Btat  ion      

at  suet  stat  ion 

1 1    of 

Brown  hydra 

Browntuil  moths 

Bryophytes  clussitlod  .     , 

Bubbles  of  oxygen  in  masses 

of  spirogyra 


106 

111 
11 


218 
212 

-  ■ 

lis 


IIS 

.  U  *  i 

17s 

• 

17s 


11 
l'.'l 


22 1 

ll  Hi 
111 

152 

lis 
lis 

111 

I 


•JO 


6 


INDEX 


References  are  to  pages 


Bubonic    plague,    a    bacterial 

disease 2.34 

Bud,   in   reproduction  of   yeast 

plant 356 

Budding1  (fig.) 287 

Budding-  cells  of  yeast   .     .     .  356 

Buds,  a  characteristic  of  stems  .  286 

Buffalo  (fig.) 158 

Bugs,  members  of  Hemiptera     .  20 

Bullfrog 123 

Bullhead  (fig.) 105 

organs  of  smell  in 109 

Bull  snake,  with  hen's  egg  in 

mouth  (fig.) 130 

after  swallowing  egg  (fig)    .     •  130 

Bull  thistle  (fig.) 396 

Bumble  bee,  carrier  of  pollen 

for  red  clover 304 

economic  value  of 35 

Burbank's  work      .     .     .     .306,402 

Burdock,  common  weed    .     .     .  334 

distribution  of  seed      ....  312 

by  animals 313 

in  blossom  (fig.) 311 

Bur  reed,  a  fruit  distributed  by 

water 314 

Bushman,  environment  of     .     .  127 
Butcher  bird,  food  of  .     .     .     22,  26 

Butter,  example  of  fat  ....  176 

flavor  of,  due  to  bacteria      .     .  349 

indirect  product  of  plants     .     .  401 

value  of  as  food 178 

Buttercup,  characteristic  mem- 
ber of  crowfoot  family      .     .  327 

study  of  pollination  of      .     .     .  305 
Butterflies,  classified    .     .     .     .  6,  20 

complete  metamorphosis  of      .  19 
Butterfly,    swallowtail,    from 

celery  worm 34 

larvae  of 28 

pollinating  Persian  lilacs  (fig.)  299 

Buzzards,  food  of 147 

C 

Cabbage,  member  of  mustard 

family 328 

plant  (fig.)      292 

Cabbages,  laboratory  study  of  404 

storage  of  food  in 294 

value  of  as  food 178 


Cactus,  giant  (fig.) 395 

Calcareous  skeleton  of  coral  69 

Calcium,  a  chemical  element     .  9 
Calcium  phosphate,  in  Pasteur 

solution 356 

Calla  lily  (fig.) 403 

Calorie,  defined 177 

Calyx,  described 296 

Cambium,  change  to  xylem  .     .  287 

change  to  phloem 287 

Cambium  layer  in  woody  stems  287 
Camel,  economic  importance  of 

(fig.) 154,  158 

Canada  ginger,  storage  of  food 

in  (fig.)    .     ...  \     ...  291 

Canada  thistle  (fig.)    ....  336 
Canal,     alimentary,     of    frog 

(fig.) 163 

of  man  (fig.) 165 

Cancer,  quacks  and 244 

Cane  sugar  in  Pasteur  solu- 
tion      356 

Canine  teeth 167 

Canker  worms 28 

Canning  of  beans 317 

Cap  fungi  (fig.) 357 

Capillaries,  described  (fig.)  .     .  202 

Capillarity 276 

Capillary  circulation  (fig.)      .  198 

Capsule,  a  form  of  fruit  (fig.)   .  308 

dehiscent  fruit 310 

fruit  of  lily 327 

of  moss 364 

Capsule  containing   eggs  of 

earthworm 83 

Caraway,   member  of    parsley 

family 329 

Carbohydrates,  a  class  of  food  169 

stored  by  bean 265 

Carbolic  acid,  a  disinfectant     .  253 

a  poison 221 

Carbon  dioxide,  a  waste  prod- 
uct of  respiration  .  .  .  .  3,  9 
formed  by  yeast  plant  .  .  .  355 
how  obtained  by  water  plants  394 
product  of  respiration  only  .  .  276 
taken  from  the  air  by  plants  .  401 
Carbonic  acid  gas,  formed  by 

oxidation 9 

Cardiac  valve  of  stomach     .  168 


INDEX 


Carnivorous  plants,  modifica- 
tions of 389 

Carpellate  cone  of  pine      .     .  .".7'.' 

Carrier  of  disease 243 

Carrion  beetle,  beneficial  insert  26 
Carrot,     membei    of     parsley 

family 329 

storage  of  food  in L's:; 

wild,  pollinated  by  fly  (fig.)     .  '_)(.»s 

Cartilage  (fig.) 186 

in  skeleton 184 

rings  in  air  passages   ....  193 

where  found 183 

Casein,  a  form  of  protein  .     .     .  1  T« i 
Catalpa,  wind-distributed  plant 

(rig.) 312 

Catalpa  twig-  (fig.) 289 

Caterpillars,     destructive     in- 
sects      28 

larvae  of  butterflies      ....  19 
stage  in  metamorphosis   .     .      17-19 

Catfish  (fig.) 105 

Catkin-like   flowers    of   wal- 
nut       327 

Catnip,  a  medicine 331 

Cat-tails  (tig.) 394 

Cattle,  escape  inspection  .     .     .  243 

value  of  to  man 154 

Caudal  fin  of  crayfish    ...  87 

Caudal  region  of  lisli        .     .     .  1«>7 
Caustic   potash  in  Fehling's 

solution 265 

Cecropia  moth  (fig.)    ....  :*> 

Cedar,  a  conifer 383 

Cedar    bird    feeding-    young 

dig-) ;;- 

Celery,  plant  (fig.) 292 

storage  of  food  in 293 

value  of  as  food 178 

Cell,  animal  (fig.) 4 

name  given  by  Hboke      .    .    •  15 

of  plenroeoccus 339 

plant  (rig) I 

unit  of  structure 4 

wall    .     . 

Cells,  various  forms  of,  in  human 

body  (fig.) 189 

Centipedes  (fig.) 92 

Central  axis  of  pine  cone  .     .  379 

Central  cavity  of  sponge  .     .  68 


,tr-    tO  /""/■ 

Central     cylinder     of     root 

(fig.) 

Central   nervous    system   of 

frog  (fig.) 118 

Central  pith  of  wood 
Central  stalk  of  fern  frond 
Cephalopoda,  classified   .     -     . 
Cephalopods,    group    of    mol- 

lu^k^    

Cere 

Cereal  foods.  Bouroe  of  .  .  . 
Cereals  <  fig.) 

list  of 

Cerebellum,  of  amphibians  .     . 

of  child 

Cerebral  ganglion  of  mollusk 
Cerebral  hemisphere  of  frog 

Cerebrum  of  man 

Certified  milk,  defined  .  .  . 
Chameleon,  a  li/;ird  .... 
Chara.  food  of  craj  fish  .  .  . 
Cheese,  example  of  protein  . 

flavor  of 

indirect  product  of  plants     .      . 

value  of  as  food 

Cheese  skipper 

Chemical  change,  defined  .  . 
Chemical  compounds  .  .  . 
Chemical  elements,  propor- 
tion of  iu  li\  iug  tliin_'-  |  fig.  i 
Chemicals,  used  to  enrich  soil  . 
Chemical  terms,   explanation 

of - 

Chemical    test    for    carbon 

dioxide 275 

Chest  cavity  of  man  .     .      194,  201 
Chestnut.  :i  dr>  fruit  (fig.)    .     . 

trees,  value  of 

Cherry,  distribution  of  Beads  of 

twigs  (fig.) 

Chickadee.  ;it  hemp  and  millet 

station n^ 

at  BUel  stati.'ti 148 

at  w  hole  grain  station 

destroyer  ol             md  lai 
oi  Lepidoptera I 

food  of i>> 

Chimney  swifts,  u-  -t  .     .     .  Ill 

u  [ngs  and  feet  of" 

China,  dependence  on  rice     .    . 


ni 

too 

119 
224 

119 
131 

101 
178 

11 

271 


8 


INDEX 


References  are  to  pages 


Chinese  silkworm 

Chipping-      sparrow,       useful 
bird 

food  of 

Chloride  of  lime 

Chloroform,  example  of  anes- 
thetic   

action  on  lipoid 

Chlorophyll,  in  leaves  of  bean 

of  pleurococcus 

Chloroplasts,     containers     of 

chlorophyll 

Choroid,  coat  of  eye  (fig.)      .     . 

Chrysanthemums,         perfect 

blooms  of     .......     . 

Cicada,  adult  and  nymph  (fig.) 

description  of 

member  of  Hemiptera  .     .     . 
Cigarette  smoking",  effect  of  . 
Cilia,  in  air  passage 

of  paramoecium 

of  sperms  of  moss,  use  of    .     . 

Ciliata,  classified 

Ciliated  larva,  of  liver  fluke     . 
Circular    muscles,    of    earth- 
worm   

Circulation,  effect  of  alcohol  on 

in  plants 

of  mollusks 

organs  of  (fig.) 

Civilization,  advanced  by  agri- 
culture      

Clam,  digestive  tube  of  (fig.) 

embryo  of  (fig.) 

example  of  mollusk     .     .     .     . 

laboratory  study  of      .... 

right  shell  of  (fig.) 

showing  foot  (fig.) 

soft-shell  (fig.) 

Clams,  artificial  raising  of    .     . 

edible      

example  of  pelecypoda     .     .     . 

fresh  water 

growing  on  oyster  (fig.)  .     .     . 
Clasping  base,  of  corn  leaf  .    . 

of  grass  leaves 

Classification,  basis  of,  in  Pro- 
tozoa   

of  birds  ...   \     .....     . 

of  plants  by  Linnaeus  .... 


28 

144 

31 

253 

221 
223 

272 
339 

272 
216 

226 
25 
25 
24 

227 

195 
50 

366 

6 

77 

80 
205 
278 

97 
199 


326 

95 

97 

6,94 

96 

95 

94 

100 

100 

100 

6 

94 

101 

281 

323 

52 
139 
303 


of 


Classification,  continued 

of  seeds 

of  living  things  .... 
Clean  milk  (fig.)  .  .  . 
Cleft  grafting"(fig.)  .  . 
Cleistogamous     flowers 

violet  (fig.) 

Clematis,  twining  petiole  (fig.) 

use  of  petioles  in 

Climbing     plants,    thigmotro- 

pism  in 

Climbing    stems    compared 

with  trees 

Clitellum  of  earthworm     .     . 

Cloaca  of  frog 

Clothing,  obtained  from  mallow 
family 

source  of 

Clover,  affected  by  darkness 

member      of      pulse       (bean) 

family 317, 

Club  moss,  related  to  ferns  .     . 

sporangium  of  (fig.)     .... 

spores  of  (fig.) 

uses  of    

Coal,  formation  of 

study  of,   in  connection   with 

ferns    

Coating  of  hairs,  use  to  Arctic 

plants 

Coats  of  pollen  grain  .  .  . 
Cob,  relation  to  corn  grains  .  . 
Cobra,  most  deadly  snake  .  . 
Cocaine,  a  poison 

cause  of  disease 

Coccus,  a  form  of  bacteria    .     . 

Cockroaches,    family    of    Or- 

thoptera  

harmful  insects 

Cocoanut,   a   fruit   distributed 

by  water 

Cocoon,  of  cecropia  (fig.)      .     • 

of  codling  moth  .     .     .     .     .     . 

Cod,  classified 

example  of  bony  fish    .... 

value  of,  as  food 

Codfish 

Codling  moth,  a  harmful  Lepi- 
doptera  (fig.) 19 

complete  metamorphosis  of 


263 
6 

348 

286 

301 

292 
294 


287 

286 

83 

116 

329 
401 
393 

318 
369 
373 
373 
374 
374 

369 

397 
299 
309 
132 
232 
232 
343 

20 
22 

314 
30 

18 

6 

106 

178 

178 

,28 
17 


INDEX 


9 


Codling  moth,  contintu  d 

description  of •"•'_' 

destroyed     by    downy     w 1- 

peckei ill 

larva  (rig.) 17 

pupa  (fig.) L8 

Cce^enterates,  examples  of  .    .  63 

described <'..'. 

Coelome  of  earthworm  .     .     .  M 

Coffee,  effect  on  ln-art  ....  -^i, 

Cold,  a  common  disease     .    .  197 

Cold-blooded  animals    .     .     .  109 

Cold  storage,  purpose  of      .     .  :;); 

Coleoptera,  examples  of  .     .     .  20 

Collar  of  corn  leaf 281 

Colonial  Protozoa  .     ,    .     .     .  58 
Colony,  hydroids      ....     66,  <>7 

Color  of  fungi,  reason  for    .     .  354 

Colors,  use  of,  in  (lowers  .      304,  389 
Columbine,  flower  of  (fig.)    304,  328 

Use  of .'  327 

Communicable  diseases    .     .  233 

deaths  from  (fig.) 234 

prevention  of 239 

Comparative  cost  of  digesti- 
ble nutrients 17s 

Comparison  of  monocotyledo- 
qous  plants  with  dicotj  ledo- 

ikius 29B 

of  pleurococcus  and  spyTOgyra  341 
of  unicellular  plants  with  mul- 

ticellular 338 

Complete     flower,    definition 

of 297 

also  perfect : -it- 
Complete  metamorphosis  of 

insects 17.  19 

Complex  flowers  of    higher 

plants W3 

Complexion,  light,  'lark   .     .     .  190 
Complex  systems  of  higher 

plants 103 

Composite  Family      ....  334 

Compound  leaves,  detineil  .     .  294 

Condor 136 

Conducting  tissue  of  pteris 

stem 370 

Cones  of  pine  (fig.)     .     377,  :;7->,  .".7'.» 

Conifers  (  fig.) ;:To 

general  characteristics     .    •    •  376 


are  t<<  pages 

Conifers,  continued 

related  forms  of 

summary  "f 

Conjugation      of     spirok'y 

(fig.) 

Consumption,  treatment  of 
Contact,  movemenl  caused  bj 
Contractile         vacuole        of 

amoeba 

Coon  ( fig.) 

Cooper  h  Hawk.  >  eonomii        i 

tils    of 

Copperhead  snake  .... 
Copper  sulphate,  in  Fehling's 

solution 

Coral  islands,  formation  of  . 

Coral  reefs 

Corals,  example  of  «  kBlent 
example  of  Ad  Inozoa 

Core,  in  pome  fruits  .... 
Coriander,  member  of  parsley 

family 

Corn,  anionni  produced  In  ' 

canned,  \  alue  of  as  f ood  . 

distribution  of 

emln-yo  leaves  of 

example  ol  moi tj  ledon  , 

flower,  described 

flower  w  1th  pist  ils  I  fig.)  .     .    . 

fruit  of  ( ti u:  ) 

germination  of  (fig.)    .... 

indehiscenl  fruits  ... 

kernels  filled  by  corn  smut  ■     , 

laboratory  Btud]   of      .... 

leaf,  description  of 

meal,  value  of  as  f 1 

member  of  grass  family  .     .    . 
one  of  first  plants  cultivated    . 
plant .  prop  roots  of  (1 
plants,  rootlet-,  of  i  i'il:  >   .    .    . 
product  Ion,  map  of      .... 

raisin-  as  an  IndUStTJ        •      . 

Importance  of 

••  seed,"  comparison  w  ith  bean 
-red.  diagram  (1  .... 

seedling 

smut .  a  parasite  on  corn  .    . 

a  fungus 

spores  of  i  fig.)     .... 

Mem    (fig.  I 


341 


II". 

•; 
310 


I 

178 

0 

7 


310 

281 
178 

318 


10 


INDEX 


References  are  to  pages 


215, 


Corn,  continued 

summary  of     ...     . 

wind-pollinated  flower 
Cornea  of  eye  (fig.) 

Corolla,  described 

Corpuscles,  red  and  white    .     . 
Cortex  of  root  (fig.)     .     .      267, 
Cortical  layer  of  kidney  .     .     . 

of  root 

Cotton,  member  of  mallow  fam- 

iiy 

production,  map  of .     .     .     . 

seed  of  (fig) 

source  of  clothing 

Cottony  cushion  scale    .     .     . 

Cotyledon  of  corn 

Cotyledons,   affected    in    bean 
blight 

of  bean 

importance  of  as  food  .     .     . 

size  of      

storage  of  food  in     ...     . 

parts  of  seed 

Cover  crop,  use  of  clover  for    . 
Cow,  example  of  mammal      .     . 

stomach  of 

Cowbirds  (fig.) 

nesting  habits  of 

Cowpox,  Jenner  and     .... 
Coxa,  part  of  grasshopper's  leg 

Coyote  (fig.) 

Crab,  soft-shelled  (fig.)      .     .     . 
Crabs,  classified 

common  name  for  crayfish  .     . 

economic  importance  of    .     .     . 

example  of  Crustacea       .     .     . 

Cranium 

Crayfish  (fig.) 

appendages  of 86 

bearing  eggs  (fig.) 

circulatory  system  of   ...     . 

digestive  system  of      .... 

example  of  Crustacea  .... 

food  and  food-getting  .... 

green  glands  of 

laboratory  study  of     .... 

life  history  of 

limited  environment  of    .     .  • . 

nervous  system  of 

organs  of  (fig.) 


321 
305 
216 
296 
197 
268 
207 
267 

329 
332 
313 
401 

27 
263 

315 

260 

261 

261 

261 

301 

270 

7 

154 

147 

142 

251 

16 

150 

91 

6 

86 

90 

6 

118 

87 

,87 

86 

90 

89 

6 

89 

90 

88 

87 

162 

90 

89 


Crayfish,  continued 

respiration  of 90 

typical  crustacean 86 

Creeping-  disk  of  snails  ...  98 
Creeping-  stem,  of  trailing  ar- 
butus (fig.) 288 

of  Canada  ginger  (fig.)     .     .     .  291 
Crenate     margins     of     mint 

leaves 331 

Cricket,  member  of  Orthoptera  20 

hai'mful  insect 22 

Crocodiles,  distribution  of    .     .  133 

example  of  reptiles 129 

Crop  of  earthworm    ....  81 
Cross-fertilization,       changes 

produced  by 311 

Cross-pollination,     advantage 


of 


305 
320 
7 
147 
148 


effect  upon  wild  plants    .     . 
Crow,  example  of  birds     .     . 
Crows,  as  scavengers    . 
at  bread  crumb  station     .     . 

at  suet  station 148 

at  whole  grain  station      .     .     .  149 

food  of 22,  27,  31 

in  nest  (fig.) 146 

Crowfoot  family,  biting  juice 

of 328 

characteristics  of 327 

members  cultivated  for  orna- 
ment     327 

products  of 327 

Crustacea,  classified   ....  86 

economic  importance  of  .     .     .  90 

Crustacea  and  related  forms  86 

Cryptogams,  classified     ...  7 

defined   6 

Cuckoos,  food  of      ....    27,  31 

Cucumber,  example  of  pepo   .  310 

Cucumber  tree  (fig.)  ....  379 
Cud,    stomach   of  animals  that 

chew  the 154 

Culex  (mosquito) 42 

•eggs  and  larvae  of  (fig.)    ...  42 

Culture,  for  protozoa    ....  49 

from  clean  milk  (fig.)       .     .     .  252 

from  dirty  milk  (fig.)       .     .     .  252 

of  bacteria 244 

Culture  plates  of  agar-agar  .  346 

Curdling  of  milk,  cause  of  .     .  348 


INDEX 


1  1 


/,■.  t,  r,  net  0  an  to  pa  . 
Curd  of  milk 265    Deer,  :i  end  cbewer l.M 


Cure  of  plant  disease     .     .     .  320 

Cures  of  quacks     .     .         .     .  •_'  II 

Curing-  of  meat,  purpose      .    .  347 

Currant,  example  of  berry    .     .  310 

Currant  worms,  caterpillars    .  19 

Cuticle  of  paramcecium     .     .  60 

Cuts,  treatmenl  of 204 

Cuttlefish,  a  cephalopod  .     .     .  99 

compared  with  squid   .     .         .  100 

Cutworms,  harmful  inseel   .     .  28 
Cyclops,    a    small    crustacean 

(fig.) 91 

Cypress  trees,  conifers    .     .     .  383 

Cypris !U 

Cytoplasm,  of  pleurococcus  339 

of  amoeba 48 

of  nerve  cells 209,  225 

of  protoplasm 

D 

Daddy-long-legs  (fig.)     .     .     .  92 

Dahlia  roots  (fig.) 285 

Dairy  cow,  model  (rig  )    .     .     .  '-'17 
Dairy   cows,  number   and  dis- 
tribution of  (fig.)      ....  249 
Dairy  stable,  model  (tig )     .     .  248 
Daisy,  a  common  weed       .     .     .  '■•'■'A 

a  composite 334 

white  (fig.) 334 

Dandelion,    a     common     weed 

(fig.) 334 

a  composite 334 

distribution  of  seed  (fig.)     .     •  312 

Daphnia 91 

Darkness,  a  universal  stimulus  :'>'.'.'< 

effect  of,  on  clover  and  ozalis  393 

Darwin  on   cross-pollination 

Davenport,  quoted 

Dead  matter    simplified    by 

bacteria 345 

Deaf.  Dumber  of 257 

Death  caused  by  insects    .     ■    .  21 
Deaths  from  communicable 

diseases  (fig.) 234 

Decay,  caused  by  bacteria    ■    .  ;;'i 

Deciduous  leaves,  defined       .  294 
Decomposition     caused     by 

bacteria -U4 


305 

256 


l.v. 

1 
310 
310 


Must ration  «>i  .volution  .    .    .     154 
Virginia,  faw  as  of  (fig         ■    .     156 
Deer-mouse    .i   nocturnal     ro- 
dent i  fig.)    .     .         .... 

Definitions  of  common   bio- 
logical terms 

Dehiscent  fruits  defined     ,     . 

forms  of  (tig-)  

Deliquescent  stems   .... 
Denuded      hills,       cause      ol 

freshets 

Deodorizers   not  disinfectants 
Department   of   Agriculture 
of  United  States,  Inspect- 
ing meal   .... 
in\  est  i-'.i'  iona  concerning 

cot  tony  cushion  scale   .    . 
Dependence,  of  fm 

of  mistletoe 

of  plants 

Dermis,  defined 

Dero  (fig.) M 

Desert    plants,    living    condi- 
tions     

Deserts,  habitat  of  plants 

Development  of  amphibians     120 

Development      of      tadpole, 
two  stages  In  I  ii-'.  >  .    . 

Devil  fish,  example  ot  cephalo- 
poda     

Dew.  use  by  Bpermsof  mosses  . 

Diamond-shaped      markings 
of  marchantia 

Diaphragm,  of  man  (fij  194,  195 

characteristic  of  mammals       .     l"-41 

passage  Of  OeSOphagUS  llir.>iiL;li       167 

Diastase,  enzyi >f  fermenta- 
tion      

Dicotyledons,  group  of  plants 
represented   by   bean,  squash, 

etc 

seeds  of  

Diet IT" 

Digestion.  ;i  life  proceed  .  • 
completed  In  intestine  •  .  • 
described »71 

effect  of  alcohol  on IK2 

in  leaves  of  Venue's  flj -trap 
laboratory  stud]  of     ....    173 


123 


12 


INDEX 


References  are  to  pages 


Digestion,  continued 

of  food  by  pleuroeoccus   .     .     . 

of  food  in  seed 

Digestive  fluids,  of  man  .     .     . 

of  starfish 

Digestive  organs,  of  crayfish 

of  man,  summary  of  .  .  161, 
Digestive  system  of  animals, 
student  report  on  .... 
Digestive  tube  of  clam  (fig.) 
Dill,  member  of  parsley  family  . 
Dioecious  flower,  defined  .  . 
Diphtheria  (germ  disease)     .  197, 

antitoxin 197, 

thirty  years  of  in  N.  Y.  state 

(fig-) 

treatment  of 

Diptera  (order  of  insects)      .     . 

described 

Direct  heating  (fig.)  .... 
Dirty  barns,  milk  from  .  .  . 
Dirty  milk,  bacteria  in  (fig.)     . 

Disease,  cause  of 

of  beans  (bean  blight)      .     .     . 
of  plants,  necessity  for  know- 
ing   320, 

of  respiratory  tract      .... 

results  of 

student  report  on 

summary  of 

Diseases    caused  by  abnormal 

growth  of  tissues      .... 

caused  by  bacteria       .... 

by  plants  or  animals     .     .     . 

by  poisons,  list  of     .... 

Disinfectants 

Disinfection 

Disk,  central,  of  starfish    .     .     . 

sucking,  of  starfish      .... 

Disk-flowers  of  composites  . 

Dissected  leaves  of  crowfoot 

family 

Distribution  of  plants  .... 

of  plant  products,  an  industry 

of  seeds,  agencies  for  .... 

of  seeds  by  animals      .... 

by  pappus  and  hooks    .     .     . 

by  water 

from  milkweed  (fig.)  .  .  . 
necessity  for 


339 
266 
171 

72 

89 

182 

164 
95 

329 
299 
234 
252 

242 
252 
20 
41 
197 
348 
319 
232 
315 

402 
197 
254 
256 

258 

233 
401 
233 
232 
253 
253 
71 
73 
334 

328 
399 
401 
312 
313 
389 
313 
313 
311 


Dividing  cells  of  pleurococ- 
cus      

Dividing  egg,  becoming  tadpole 

(fig.) 

of  frog  (fig.) 

Division  of  labor 

in  man 

in  sponge 

in  volvox 

Dodder,  twining  stem  of  (fig.)  . 

Dog,  skeleton  of  (fig.)    .... 

Dogtooth  violet,  stems  of    .     . 

Dorsal  blood  vessel  of  earth- 
worm      

Dorsal  surface  of  earthworm 

Dough  in  bread  making     .     . 

Douglas  fir.  economic  value  of 

Downy  woodpecker,  a  perma- 
nent resident 

food  of    

Dragon  flies,  enemies  of  mos- 
quito    

member  of  Odonata     .... 

Dredging,  necessity  of      .     .     . 

Drills,  a  method  of  planting  .     . 

Drink,  impairment  of  scholar- 
ship by  (fig.) 

skill  and  endurance  impaired 
oy  (fig.) 

Drink  and  assaults  (fig.)     .     . 

Drones  (bees) 

Drowning,  a  form  of  suffocation 

Drupes,  defined 

Dry  beans,  ability  of  to  grow    . 

Dry  fruits,  bean  an  example  of 

Drying,  protection  of  bacteria 
from 

Drying  fruit,  purpose  of  .     .     . 

Dry  season,  effect  of  on  annual 
ring 

Dry  seasons,  effect  of,  on  size 
of  cells .     . 

Ducks,  feet  of 


E 


339 

122 

122 

56 

164 

57 
56 

288 
150 

285 

82 

80 

179 

385 

141 
144 

42 

20 
387 
402 

221 


219 
222 
35 
196 
310 
264 
310 

345 
347 

290 


Eagle,  a  scavenger 
claws  of  ... 
head  of  (fig.)  .  . 
wings  of      .     .     . 


378 
137 


147 
137 
140 
136 


ixi)i:x 


13 


Rqfen  run  b 

Ear,  affected  only  by  Bound    .     .  21 1 

balancing  organ 218 

membrane  of  froj; Ill 

of  grasshopper 11 

pistillate  flower  of  corn    .    .    .  298 

plan  of  (fig.) 218 

sense  organ 216 

wax  in L'ls 

Earthworm,    economic    impor- 
tance of 84 

example  of  worms 6 

excretions  of 83 

front  end  of  nervous  system  of 

(fig.) 82 

illustration  of  true  worms   .     .  80 

laboratory  study  of      ....  82 

life  history  of 8.'5 

locomotion  of 80 

limited  environment  of    .    .    .  1<»'- 

organs  of  (fig.) 81 

respiration  of 8ii 

ventral  surface 80 

Easter  lily  (tig.) 300 

pollination  of 307 

X-ray  of  (fig.) 327 

Echinoderms  classified      .     .  6 
Economic  importance  of  am- 
phibians    127 

of  birds 114 

of  coelenterates "<> 

of  crustaceans 90 

of  earthworms 84 

of  fern  group 374 

of  gymnosperms 384 

of  lichens 361 

of  mammals 164 

of  mollusks I'*" 

of  paramoecium 61 

of  plants 320 

of  starfish  group 74 

Economic  insects 20 

Economic  interest  in  plants  .  4<mi 
Economic   phases   of   grass- 
hopper    22 

Economic  point  of  view  in 

study  of  plants     ....  320 

Economic  value  of  mosses    .  366 

Ectoderm,  of  sponge    ....  59 

of  hydra ,i:i 

Ectoplasm  of  sponge      ...  1^ 


.//•.'  /<>  page* 

■  Edible  clams,  nam. •«,  ..f    .     .     .     L0Q 
Edible  mollusks.  Hal  ..f  .     .     .     L00 
Edible  pulp  of  cherry,  factor 
in  .list  rihiit  ion 

Eels,  migrations  of 1 1'» 

Efferent  fibers 213 

Efficiency  centers  of 

brain 224,220 

Egg,  a  reproducl i\ <•  cell    ...        i 

white  of,  example  of  protein 
Egg-capsule  of  grasshopper 

(fig.) IS 

Egg  cell  (female  parent)  .    .    . 
fertilization  ..f.  in  plants     .     .    300 

Vblvoi  (fig.) 06 

Egg-plant,  a  I i  plant  ..f  night- 

Bhade  family 

Eggs,   of    frog    (fig.),  develop- 
ing   121,  122 

of  grasshopper  (fig.)    ....      L0 

of  ladybug  (fig.) 26 

of  Land-locked  salmon  (fig. )     .110 

of  moss  plant 363 

Egyptians,  use  of  beans  by  ,     .  -;1T 
Elbow,    normal     and     broken, 

X-ray  photograph  (fig.)    •     ■  180 

Elk  (fig.) 150 

Elm.  leaf  (fig.) 

twig  (fig.) 289 

Embryo,  corn,  position  of     •    • 

growth  of,  in  o\  ulr      ....  ■"■"! 

heart  of 

Of  clam  (fig. )  .  91 

of  coral 

of  Liver  flake "" 

parts  of :;"i 

Bac,  content  a  of 

vigorous,  result  of  cross-polli- 
nation  300 

Employment      afforded      by 

plant  industries  .  .  .  .  »oi 
Enamel,  effeel  of  bacteria  on  167 
Encystment  of  amoeba  .     .     . 

Endoderm,  of  root 

of  sponge 

Endoplasm 18 

Endosperm,  food  supply  of  corn 
of  corn  uraiu 

of  coin,  used    for  growth   oi 
dling 


14 


INDEX 


References  are  to  pages 


Endurance     and     skill     im- 
paired by  drink  (fig.)    .     . 
Enemies,  of  the  bean    .... 

of  corn  

of  lepidoptera 

of  man 

Energy,  source  of,  in  man     .     . 

yielded  by  bean 

English      sparrow,      attracts 

other  birds 

destroys  weevils 

eats  larvae  of  Lepidoptera    .     . 
permanent  resident     .... 

scientific  name  of 

English  walnut,  protein  in  .     . 
Enlarged  base  of  onions,  stor- 
age of  food  in 

Enriching  the  soil  by  nitro- 
gen      

Environment,  denned  .... 

discussed 

illustrated  by  development  of 

frog 

Enzyme,  of  gastric  juice  .     .     . 

of  yeast  plant 

secreted  by  bacteria    .... 
Ephemeridae,     an     order     of 

insects     

Epidemics,  of  diseases,  costli- 
ness of 

sore  throat  (fig.) 

Epidermal   tissue    of   pteris 

stem 

Epidermis,  of  agave,  section  of 

(fig.) 

of  bean  root  (fig.) 

of  leaf  (fig.) 272, 

of  root 

of  rootlets 

of  xerophytes,  character  of  .     . 

outer  layer  of  skin 

Epiglottis 

Epileptics,  number  of  ...  . 
Epiphytes,  definition  of    .     .     . 

habitat  of 

Epithelium,  ciliated  (fig.)      .     . 

columnar  (fig.) 

flat  (fig.) 

Eskimo,  surroundings  of  .  .  . 
Esophagus,  of  crayfish     .     .     , 


219 
315 
316 
30 
316 
1 
317 

148 
27 
31 

141 
7 

170 

294 

318 

10 

126 

125 
172 

354 
345 

20 

255 
243 

370 

396 
268 
274 
267 
269 
396 
189 
193 
257 
399 
399 
189 
189 
189 
127 
89 


Esophagus,  continued 

of  earthworm 81 

of  frog 116 

of  man 167 

Ether,  an  anesthetic      ....  221 

test  for  oil 266 

Eustachian  tube  (fig. )     .    .     .  218 

of  frog 114 

of  man 166 

Evaporation,  prevention  of,  in 

experiment 295 

Evaporation  of  perspiration, 

effect  of 190 

Evergreen,  leaves  defined    .     .  294 

trees,  examples  of 286 

Evergreens,  characteristics  of  376 

Evolution,  theory  of     ....  123 

Examples  of  plant  societies  393 
Excitable          temperament, 

heart  tracing 228 

Excretion,  a  life  process  ...  2 

definition  of    ......     .  3 

in  crayfish 90 

of  hydra 65 

of  man 206 

of  mollusks 97 

Excurrent    stem     of     ever- 
greens    286,  377 

Exercise,  benefits  of     ....  195 

necessary  to  keep  one  fit      .     .  240 

value  of 204 

Exercising,  out  of  doors  .     .'    .  194 

to  keep  well 351 

Exhalent  pores 58 

Exhalent  siphon  of  clam     .     .  94 

Exoskeleton,  of  crayfish     .     .  88 

of  grasshopper 15 

of  lobster,  molted  (fig.)    ...  87 
Experiment,  to  show  produc- 
tion of  carbonic  acid  in  plants  275 
performed  on  plants     ....  403 

Expiration,  defined 194 

Explosion    of   fruit    case  to 

scatter  seeds 312 

Extinct  animals,  remains  of     .  125 

Extinct  plants,  remains  of  .     .  125 

Eye,  section  of 216 

Eyeball 215 

Eyelid 215 

Eyes,  of  fish 109 


INDEX 


15 


/.'•/•  n  nee* 

Eyes,  continued 

of  frog lit 

of  grasshopper 11 

of  man,  care  of        217 

of  Nereis .si 

of  vertebrates 215 

F 

Faeces,  removal  of 17." 

Fainting-,  cause  of 208 

Fangs  of  rattlesnake      .     .     .  233 

Fats,  absorption  of 174 

furnished  by  animals  ....  17" 

nutrients 1 

Fawns  of  Virginia  deer  (fig.)  166 

Feathers,    a    characteristic    of 

birds 136 

of  birds,  modifications  of  skin  190 

Feeble-minded,  number  of  .     ,  257 

Feelers,  of  bullhead      ....  109 

of  grasshopper 14 

Feet  of  birds,  different  kinds 

of  (tig.) 139 

Fehling's  solution,  formula     .  265 

test  for  sugar 266 

Female  bobolink  (fig.)  ....  14"> 

grasshopper  (rig.) 11 

strobilus  of  pine .">7(.» 

Femur,  broken  (fig.)     .    ...  187 

of  grasshopper L6 

Fennel,    member     of     parsley 

family :v_,(.i 

Fermentation,  cause  of   .    .     .  350 

effect  of 345 

produced  by  enzymes  ....  345 

tubes  (tig.) 355 

Fern,  forked  veins  of  (fig)  .     •  371 

garnet  ophyte -;7l 

life  history  (fig.)      .    .    .    .371,372 

Fern  group,  plants  belonging  to  373 

Ferns,     example     of     pterido- 

phytes 7 

field  study  of 373 

habitat  of •"'<'•,., 

laboratory  study  of      ....  373 

Ferns  and  their  Allies    .     .     .  .".o'.i 

in  relation  to  water     ....  375 

summary  of 375 

Fertilization,  defined  .    .    .  68,  '-"•>'., 


are  to  pagt  * 

Fertilization,  continued 
"i  egg  ••ell  in  the  o\  iii.-    .    .    , 

of  frog  

Fertilized  egg  cell,  beginning 

of  new  organism 

of  volvox    

Fertilizers,    use   of,    to    supply 

elements 

Fibers  in  blood 

Fibrinogen,    in     format  ion     of 
clot 

Fibrous    roots,    of    buttercup 
(fig.) 

of  corn 

of  grasses 

Fibrovascular   bundles,  cells 
of 

in  leaves 

in  root    

structure  of 

use  of,  in  photosynl  bests 
Field  study,  of  f.-rn^     .     .     .     . 

of  gymnosperms 

of  insects    

Field  suggestions,  mammals  . 
Filaments,  described    .... 

Finches,  beak  of 

Fin  rays 

Fins,  of  ftah 

use  of,  in  balancing  and  steer- 
ing   

Fires,  forests  destroyed  by    .    . 

l>iv\ .niion  of,  by  national  g 

eminent 

Fire  slash  (fig.) 

Fire    train    in    the     Adiron- 

dacks  (fig.) 

Fireweed  in  plant  bu< ssion 

Firewood,  furnished   by  b 

family 

Fireworks,  ose  of  spores  ol  club 

iiio>s  in 

Firs,  conifers 

Fish,  care  of  young 

skeleton  of  I  fig.  I 

mi  in  ma  rv  of 

Fish  hatcheries 

Fishes,  bony 

circul.it  ion  of 

classified 


121 


271 

a .  i 


i^n 


12 

137 
107 

1"7 

107 


100 


112 

112 

lb) 

106 
109 

8 


16 


INDEX 


References  are  to  pages 


Fishes,  continued 

food-taking 108 

reproduction  of 109 

respiration  of 108 

scales  of  (fig.) 107 

special  senses /)f 109 

with  lungs 106 

Fish  fry,  young  (fig.)     ....  Ill 


showing  volk  sac  (fig.) 


Ill 


Fission,  a  form  of  cell  division  49,  339 

Flaccid  cells 273 

Flagellata,  group  of  Protozoa  .  53 

Flagellate  protozoa  (fig.)  .     .  52 
Flat  worms,  classified      .          .  6,  70 

Flavor,  improvement  of    .     .     .  311 

of  butter 345,349 

Flavors  caused  by  fermentation  345 

by  bacteria 345 

Flax,  family 329 

requires  cultivation     ....  329 
useless  parts  of  plant  removed 

by  bacteria 345 

Fleas,  member  of  Siphonaptera  20 

Flesh-eating  animals      .     .     .  161 

Fleshy  fruits 309 

Fleshy  stalks  for  storage      .     .  294 

Fleshy  stems  for  food  storage  .  285 

Flies,  carriers  of  bacteria       .     .  347 

classified 6 

members  of  Diptera     ....  20 

Flipper  of  seal 152 

Floods,  cause  of 385 

damage  caused  by 386 

prevention  of 385 

Florida  alligator  (fig.)     ...  133 

Flour,  food  elements  in      .     .     .  179 

Flower,  of  Columbine  (fig.)  .     .  304 

of  corn  with  pistils  (fig.)     .     .  299 

of  mallow  (fig.) 331 

of  mint  (fig.) 303 

of  sweet  pea  (fig.) 298 

violet,  cleistogamous  (fig.)  .     .  301 

Flower  bud 289 

Flowering  plants 323 

common  families 323 

summary  of 336 

Flowering    sage,    adaptations 

for  insect  pollination    .     .     .  304 
Flowerless  plants,   classifica- 
tion of 7 


food 


Flowers,   field  and   laboratory 
study  of 

of  bean,  organs 

wind-pollinated  .     .     . 
Flycatcher,  great-crested 

of 

Flycatchers,  eaters  of  larvae     . 

food  of    

Flying  squirrel  (fig.)   .... 
Fly  pollinating  wild   carrot 

(fig-) 

Foliage,  rank-scented  leaves  of 

nightshade  family     .... 

Food,  a  vital  condition      .     .     . 

care  of    

definition  of 

first  plants  to  be  cultivated  for, 
list  of 

for  reindeer  in  Arctics      .     .  361 

fungi  a  source  of 

necessary  to  keep  one  fit      .     . 

of  animals,  student  report  on  . 

of  bacteria 

of  clam 

of  plants,  study  of 

of  snakes 

of  starfish  —  how  taken    .     .     . 

pecuniary  value  of 

storage  —  Canada  ginger  (fig.) 

stored  in  cotyledons  of  bean     . 
Food-getting  by  animals  .     . 

by  grasshopper 

Foods  

Foodstuffs  in  bean      .... 
Food-taking  of  earthworm  .     . 

of  starfish 

Food  vacuole 

Foot  of  moss  sporophyte  .     . 
Foraminifera,  one  of  the  (fig.) 
Forest  fires,  harming  of  soil  by 
Forest  reserves  .     . 
Forestry  in  Europe 
Forests,  extent  of  in  U 

importance  of      .     . 

patrolling   .... 

proportion  necessary 

tall  trunks  of  pine  in 
Forked  veins  of  fern  (fig.) 
Formaldehyde,  a  preservative 

gas 


302 
260 
305 

26 

31 

145 

152 

298 

334 
314 
240 
169 

326 

,  366 
354 
240 
171 
344 

96 
320 
132 

73 

177 

291 

261 

2 

14 

1 

265 

84 

73 

48 
366 

52 
387 
387 
387 
385 
385 
387 
385 
377 
371 
348 
253 


i.\i)i:.\ 


Refert  net  b 

Formalin,  in  milk 180 

used  as  disinfectant      ....  'J.V. 

Fossils,  described 124 

shells  of  animals  qow   extinct 

(fig.) 124 

Foul  breath  caused  by  bac- 
teria    KIT 

Foxes  (fig.) 151 

Fox  sparrows,  transients     .     .  141 
Fox     terrier,     comparison     of 

primitive  horse  with     .    .    .  154 
Freezing1,  protection  of  bacteria 

from 345 

Fresh  air,  a  condition  for  health  240 

aid  in  curing  consumption    .     .  •_'■">•; 

Freshets,  cause  of 386 

Fresh-water  planarians      .     .  7(i 

Frog",  bull,  development  of    .     .  L23 

central  nervous  system  of  (fig.)  118 

common  (fig.) 114 

description  of 113,114 

eggs  (tigs.) 120, 121 

example  of  amphibians     ...  7 

enemies  of 115 

food  of 115 

green,  development  of      .     .     .  123 

habitat  of 114 

internal  structure  of    ....  115 
laboratory  study  of      .     .     .114,  120 

leopard,  description  of      ...  Ill 

organs  of  (fig.) 11<>,  117 

reproduction  of 117 

respiration  of       115 

tree  (fig.) 126 

Fronds  of  pteris 370 

Fruit,  buds  of  cherry  (fig.)     .     .  289 

defined 308 

of  apple  (fig.)      309 

of  beau  (fig.) -;i|7 

of  bean  and  corn 308 

of  corn  (fig.) 307 

of  pine 

of  poppy  (fig.) ■"■"* 

production  in   connection   with 

storage  roots 283 

steps  in  de\  elopmenl  of  .    .    •  308 
Fruits,  distributed   by  animals 

•  tig.) 311 

by  wind  (fig.) 312 

distributers  of  seeds     .     .     .     .  311 


by 


are  to  pagt 

Fruits,  tontinvu 
furnish  luxuries  of  food  • 
new     varieties     produced 
cross-pollination  . 

of  rose  family 

w  itli  hooks  (fig.) 

Fruits  and  seeds  in-  i     .     .     . 

Fry.  distribution  of 

Fuel,  hardwood  1 1  lurce  of 

Fumigants 

Functions,  definition  of    .    .    . 
Fundamental  tissue  of  pteris 

stem 

Fung-i,  action  in  changing  lava 

1"  --oil 

classified 7 

conditions        favorable       for 

growth         

summary  of 

Fungus,  an  enemy  of  corn     .    . 

Furniture,  lumber  for  .... 

Furs,  as  clothing 


::il 

401 

.11 
Ml 
111 

1 


362 
291 


G 


Gall  bladder  of  i !.>_'     ....     117 

Gall  flies,  example  of  ll\  menop- 
tera 20 

Gametes,  defined 341 

of  moss 

Gametophyte  or  sexual  gen- 
eration of  moss     .... 

Gametophytes  of  moss      .     . 

Ganglia,  of  clam 

<>f  earthworm 

Garden  slug,  shell  of  .... 

Garden  vegetables,  belonging 
to  mustard  family    . 
to  parslej  family      .... 

Garter  snake,  harmless 

Gas,  a  form  of  matter   .... 
use  in  bread  making    .... 

Gastric  gland  (li-.  i      ,     .       169,171 

Gastric  juice 171 

Gastric  mill,  of  crayfish   .     . 

Gastropoda  rlussinVd     .      .      . 

Gtoese,  feel  "t 137 

wild,  t  ransientfl l  '1 

Gelatinous        secretion       of 

earthworm 


18 


INDEX 


References  are  to  pages 


Genera  Plantarum,  published 

by  Linnaeus 303 

Geometrid  moth  (rig.)     ...  32 

Geotropism,  defined     ....  284 

Geranium,  life  processes  of  .     .  259 

simple  leaf  of 294 

slip,  roots  of 284 

study  of  flowers  of 302 

Germ,   a  name   for   unicellular 

organisms 343 

diseases 233 

Germination,  laboratory  study 

of 265 

of  corn  (fig.) 277 

Germs 233 

a  name  for  bacteria      ....  343 

in  dust  in  houses 235 

of  disease  carried  by  insects     .  21 

Giant  cactus  (fig.) 395 

Gila  monster,  poisonous  lizard 

(fig.) 131,  135 

Gill,  cover 107 

Gill  rakers 108 

Gill  scoop,  of  crayfish  ....  90 

Gill  slits 104 

Gills 107 

of  clam 96 

of  crayfish 90 

Girdle,  pectoral 105 

pelvic 105 

Gizzard  of  earthworm  ...  81 

Gland  of  starfish 72 

Glandular  hairs  of  sundew    .  390 

Glassy  sponge,  skeleton  of  .     .  61 

Glomerulus  of  kidney    .     .     .  208 

Gluten  changed  by  heat    .     .  179 

Glycerin  formed  by  zymase  179 

Glycogen,  stored  in  liver      .     .  174 

Gnats,  eaten  by  birds    ....  145 

Goats,  economic  importance  of  154 

Golden  rod,  a  common  weed     .  334 
Goldfinch  at  hemp  and  millet 

station 148 

Goldfish,  a  typical  bony  fish      .  106 

killed  by  tobacco  smoke  .     .     .  230 

Gonium  (fig.) 55 

Gophers,  harmful  mammals      .  155 
Government    inspection,    of 

meat 78,  242 

of  oyster  beds 102 


Grafting,  effect  of 402 

kinds  of  (figs.)     ....      286,  287 

Grain,  differs  from  bean    .     .     .  262 

food  for  birds 149 

of  corn,  a  form  of  fruit    .     .     .  310 

Grains,  large  numbers  of  .     .     .  314 

Grantia  classified 6 

described 58 

Grape,  example  of  berry  .     .     .  310 

Grapevine,  wild,  like  liana  .     .  287 

Grass  family 323 

compared  with  rose  family  .     .  328 

Grass,  life  processes  of      .     .     .  259 

monocotyledon 263 

wind-pollinated  flower     .     .     .  305 

Grasses,  flowers  of 323 

importance  of,  as  food     .     .     .  400 

in  plant  succession 400 

Grasshopper,  classified    ...  6 

classification  of 19 

described 12 

foot  of 16 

hairworm  in  body  of  (fig.)  .     .  79 

injurious  to  corn  plants  .     .     .  316 

laboratory  study  of     ...     .  13 

laying  eggs  (fig.) 15 

life  history  of 15 

member  of  Orthoptera     ...  20 

mouth  parts  of  (fig.)    ....  14 

parts  of  (fig.)      .......  13 

representative  animal      ...  1.1 

structure  of 19 

Gravity,  influence  of,  on  roots  .  284 

Gray  squirrel  (fig.)      ....  151 

Gray  substance  of  nerves      .  211 
Great-crested        flycatcher, 

food  of 26 

Great  northern  shrike,  winter 

visitant 141 

Grebe  (fig.)       136 

Greeks,  use  of  beans  by    .  317 

Green  Algge 338 

Green  frogs,  development  of    .  123 

Green  hydra,  habitat  of  .     .     .  66 

Green  manure 270 

Green  manuring 318 

Green  turtles 131 

Gristle,  defined 184 

Groove,  on  underside  of  starfish  73 

Grosbeaks,  beak  of 137 


INDEX 


19 


Ground  birds,  wind's  «>f    .     .     .  136 

Grouse,  a  seed  eater     .    .    .    .  117 

at  whole  grain  station      .     .     .  1 19 

Growth  of  bean  embryo    .     .  264 

Grubs,  larvae  of  beetles     .     .    .  19 

of  bean  weevil -  •  l *  > 

Guard  cells,  of  fern  Btomata  373 

of  stomal  a 273 

Gullet,  of  paramoecium     .    .    .  50 

Gulls,  sailing  birds 136 

herring  ( fig.) 137 

Gums,  effect  of  tartar  on  .      .     .  fi.7 

Guttation  drops,  defined     .     .  -74 

Gymnosperms,  by-products  of  384 

classified 7 

discussed 376 

field  study  of 383 

reason  for  name 381 

student  report  on 383 

use  of 384 

Gypsy  moths,  injurious  insects  28 

H 

Habitat,  of  evergreens  ....  381 

of  mosses 364 

of  Protozoa 46 

Habits  of  plants,  of  interest  to 

fanner 402 

Haemoglobin  in  corpuscles  .     .  197 

Hair,  origin  of 190 

Hair  snakes 78,  79 

Hair  worm 7  s 

in  body  of  grasshopper  (fig.)     .  79 
Hairs  on   leaves  of   Venus's 

fly-trap "''.'1 

Hairy  woodpecker  i  fig.)     .     .  H7 

Halibut,  value  of  as  food  .     .     .  ITS 
Hand,  superficial  lymphatics  ol 

(fig.)    .     •     •     •' 204 

Hard  palate 166 

Hardwood,  forests,  described     .  388 

trees,  large  flowering  plants    .  323 

Harmful  bacteria 343 

Harvest-man,  harmless  arach- 
nid    91 

Hawk,  Cooper's 148 

example  of  bird 7 

marsh 146 

red-shouldered 148 


are  to  /"'.'/■ 

Hawk,  contin 

red-tailed 

sharp-shinned 

Hawks,  beneficial  birds  ami 

claw  s  of 

Hawkweed,  a  common  weed 
Hay  infusion  for  protozoa 
Head,  of  fish 

ol  grasshopper 

ol  rat  t  lesnake  book  lug  p< 

glands  (fig.)      .     . 
of  young  eagle  (fig.) 
Headache  medicines 
Head  end  of  earthworm    .     . 
Heads,  inflon  bc<  nee  of  compos- 
ite family 

Head-thorax  region  of  cray- 
fish       

Headwaters    of    rivers    pro- 
tected     

Health 

Healthy  bodies  and  bacteria 

Hearing- 

Heart  (fig.) 

and  lungs  (fig.) 

center 

nuisi  le  ••■■Us  t  fig.  i 

of  craj  fish 

valves  of     

Heart    and    blood-vessel- 
man     

Heart-shaped   body,    prothal- 

lium  oi  fern 

Heat  and  pressure.  Influence 
of  in  forming  coal    .... 
Heating1,  common  methods 

hot  air  (fig.) 

milk,  eft.  ct  of  on  bacteria    .    . 

strain  (fig.) 

protection  of  bacteria  from  . 

Hedge  nettle  iti-.  > 

Heel  of  man    ....... 

Hellebore,  sourer  of  •     • 

Helmholtz  on  alcohol     .     .     . 

Helpful  bacteria 

Hemiptera.  discussed  .... 

order  of  insects 

Hemlock,  bark,  use  oi 

Colics   Of   (fig.) 

conifer 


143 
148 

1  .7 

• 

19 

13 


l   l 
l»<> 

Sii 


•: 


218 
201 

22 1 

190 
197 
187 

10 


20 


INDEX 


References  are  to  pages 


Hepatica,  example  of  incom- 
plete flowers 

Heredity,  discussed 

of  disease    

Hermit  crabs,  economic  impor- 
tance of 

Herons,  beak  of 

Herring,  economic  importance  of 
Herring-  gulls  (fig.)  .... 
Hibernation,  defined    .... 

study  of 

Hickories,  members  of  walnut 

family 

Hills,  a  method  of  planting     .     . 

Hilum  of  bean 

Hinge  of  clam        

Hinge  ligament  of  clam  .     .     . 

effect  of  starfish  on  .... 
Hinge  teeth  of  clam     .     .     .     . 

Hip  bones  of  man 

History,  of  bean  plant  .... 

of  corn  plant 

Hogs,  fed  on  beans 

inspection  of 

Hollow  bones  of  birds  .  .  . 
Hollow  stem,  of  horsetail     .     . 

of  parsley  family 

Hollyhock,  member  of  mallow 

family 

Home  making,  work  of  women 
Home   study   of  moths    and 

butterflies 

Honey,  amount  of  carbohydrate 
in 

locust,  seedlings  of  (fig.)       .     . 

made  from  nectar  by  bees    .     . 

value  of  in  U.  S 

Honeybee,  discussed    .... 

stages  in  development  (fig.) 

worker,  queen,  drone  (fig.)  .     . 

Honeybees      clustering      at 

swarming  time  (fig.)     .     . 

Hoofs  of  cattle,  origin  of    .     . 

Hooks,  on  fruit  of  burdock    .     . 

on  seeds,  use  of 

Hookworm  disease  .... 
Hop  lice  destroyed  by  lady- 
bugs  

Hops,  use  of,  in  manufacturing 
of  beer 


302 
125 
255 


91 
137 

106 
137 
115 
159 

327 

402 

260 

96 

96 

73 

96 

187 

317 

320 

316 

243 

138 

374 

331 


329 
257 

33 

170 
281 
297 
39 
34 
35 
34 


36 
190 
313 
389 
239 

26 

355 


Horehound,  a  medicine    .     .     .  331 

Horned  pout  (fig.) 105 

Horned  toad,  a  lizard  (fig.)    129,  131 

Horns  of  cattle,  origin  of    .     .  190 

Horse,  classified 7 

discussed 153 

evolution  of 154 

use  of 155 

Horse-chestnut,        compound 

leaves  of 294 

seedlings  (fig.) 281 

twig  of  (fig.) 288 

woody  stem 287 

Horse-radish,  member  of  mus- 
tard family 328 

Horsetail  (fig.) 374 

joints  of  stem 374 

Horsetails,    members    of    fern 

group 373 

related  to  ferns 369 

Host,  defined    .......  31 

of  liver  fluke 77 

Hot  air  heating  (fig.)  .     .     .  195,  196 

House  flies,  eaten  by  birds   .     .  145 

Housefly  (fig.) 41 

bacterial  growths  from  (fig.)    .  250 

bacteria  and  mold  from  (fig.)  .  251 
House      sparrow,       scientific 

name  for 7 

Houses,  source  of  materials  for  401 

Human  biology 161 

Human  stomach,  X-ray  photo- 

•    graph  of  (fig.) 168 

Humming  birds,  beak  of     .     .  137 

summer  residents 141 

Humor,  aqueous 216 

vitreous 216 

Humus  destroyed  by  fires     .  387 

Hydathodes,  defined  ....  274 

Hydra,  cell  layers  in  (fig.)     .     .  65 

diagram  of  (fig.) 64 

example  of  coelenterate   ...  6 

laboratory  study  of     ...     .  66 

microphotographs  of  (fig.)    .     .  63 
microphotographs  of  body  wall 

of    ... 64 

Hydra-like  animals  described  63 

summary  of 70 

Hydras,   examples  of   coelente- 

rates 63 


ixi)i:x 


21 


/,'  f{  rerun  a 

Hydrastis,  source  of    ...     .  327 
Hydrochloric    acid    in    arti- 
ficial gastric  juice   .     .     .  173 
Hydrogen,    proportion    of    in 

plants  and  animals  ....  8 

Hydroid.  bougainvillea  (fig.)  »>o' 

colony  thai  Looks  like  a  plant 

(fig.) 67 

medusa  (fig.)  .    .  » .7 

obelia     microphotograph      of 

(fig.) 66 

Hydroids,  described     ....  <;<; 

examples  of  coelenterates     .    •  63 

Hydrophytes,  definition  <>f  .    .  394 

finely  divided   Leaves  of    sub- 
merged forms 394 

waterlilies  (rig.) 393 

Hydrotropism,  detined    .     .     .  284 

in  roots 284 

Hydrozoa,  classified     ....  6 

Hymenoptera,  discussed      .     .  :'«l 

order  of  insects 20 

Hyphae  of  bread  mold    .     .     .  .V>7 

Hypocotyl.  pari  of  embryo  .     .  •"•||i 

part  to  grow  first 261 

use  of,  to  embryo 261 

I 

Ice,  a  form  of  water       ....  9 

use  of ,  in  caring  for  milk     .     .  .".is 

Ice  cream,  dangers  from  .     .     .  350 

manufacture  of 350 

Ichneumon  flies  laying  eggs 

in  trees  (fig.) W 

Ichneumons,  discussed     .     .     .  39 
enemy  of  Lepidoptera .    .    .    .  28 
members  of  order    Hymenop- 
tera         ....  20 

Imbecility 232 

Immunity 26S 

denned 251 

Immunization 'S<- 

Imperfect  flower,  kinds      .     .  302 

of  corn 298 

Improvement       of       plants, 

methods  of W2 

Incisor  teeth 166 

Incomplete  flower,  part  lack- 
ing in $•- 


/"  pages 

Incomplete  metamorphosis 

ol  tree  cricket  (fig.) 
Indehiscent  lr  . 
Independence  of  plan 
Independent     existence 
moss  gametophyte  . 
India,  dependence  "n  i . 

Indian  pipe 

Indians,  use  <>f  beans  bj    . 

environment  of   . 


of 


Indigestion 

causes  of 

tablets  for 

Indirect  heating  (fig.)     ■     .     . 

Indistinct  ring.left  by  bud  scales 
produced  by  droughl   .... 

Inefficiency,  caused  !>y  tempo- 
re iv  sickness 

Influence  of  alcohol  on  de- 
velopment  of   brain     .     . 

Infusoria 

Inlnilent  pores 

Inhalent  siphon  of  clam  .     .     . 

Inhalers 

Inherited  diseases      .... 

Inner  chamber  of  eye  ui. 

Inner  coat  of  pollen  grain 

Inner  ear  (tig.)     ....      JIT, 

Inoculation 

Inorganic  foods 

Inorganic  matter 

Insanity 


16 

17 

••1 

1.7 
180 

181 
196 


Insect,  group,  divisons  of 

pollination 

\  Lsitors,  Btudj  of 

Insecta    

Insect  enemies  of  bean  plant 
Insects,  acti\  [ties  of      .     .     .     . 

carriers  of  bacteria      .    .    .    . 

de\  ices  for  attracting  .    .    .    . 

examples  of  Arthmpoda 

field  study  of 

life  bistorj  "i      

nhjeet  iii  \  isit  tng  tl"\\  en 
Inspection  of  meat 
Inspiration,  defined 
Insulation  of  nerve  ftbei 
Integument,  development 

of  bean 

of  o\  ales 


M 

172 
10 

\\i 

12 

194 
301 

• 


22 


INDEX 


References  are  to  pages 


Intercellular  spaces  ....  274 

Interdependence  of  plants    .  361 

Internal  gills 122 

lungs 122 

structure  of  earthworms,  labo- 
ratory study  of 82 

Interrelationship  of  animals  61 

Intestine 168 

Invertebrates 6,  103 

Inverted  image 217 

Involuntary      muscle     cells 

(fig.) 189 

Iodine  test  for  starch     .     .     .  265 

Iris  of  eye  (fig.) 216 

Iron 9 

Irregular  corolla  of  saliva       .  304 

Irregular  flower  of  violet      .  302 

Irregular  flowers,  denned  .     .  302 

Irritability 2 

Ivy,  adventitious  roots  of  .     .     .  404 

aerial  roots  of  (fig.)    ....  284 


Jack-in-the-Pulpit,  storage  of 

food  in  stem  of 285 

Jaw  bones  of  fish 106 

Jaw  of  man 166 

Jellyfish,  example  of  coelenter- 

ate       6 

belonging  to  hydra  group     .     .  63 

Jenner,  vaccination 251 

Jewelweed,  explosive  fruit  of .  312 
Jimson  weed,  member  of  night- 
shade family 331 

Juice     of    mustard    family, 

characteristics  of      .     .     .     .  328 
Juice  of  the  buttercup,  char- 
acteristics of 328 

Junco  (fig.)       144 

at  hemp  and  millet  station      .  148 

at  suet  station 148 


Katydids,  a  family  of  Orthop- 

tera 20 

Keel  of  bird's  breastbone       .     .  138 

Keeled  sternum  of  bird     .     .  138 


Kernel,  comparison  with  bean 

pod 262 

Kidney,  section  of  (fig.)    .     .     .  207 

Kidneys  of  frog 117 

King  bird  (fig.) 145 

food  of 145 

Kingfisher,  nesting  habits  of    .  142 

(fig.) 146 

Koch,  discoverer  of  Bacillus  tu- 
berculosis        235 

of  tuberculosis  test  ....  349 

study  of  bacteria  by    ...     .  351 


Laboratory         experiments 

with  leaves  ....      275,  295 

Laboratory  study,  of  bacteria  346 

of  bean  seed 261 

of  bread  mold 360 

of  ferns 373 

of  foodstuffs  in  seeds  ....  266 

of  grasshopper 13,  16 

of  gymnosperms      ...          .  384 

of  leaves  for  storage    ....  404 

of  live  fish 107 

of  moss 366 

of  moth  and  butterflies    ...  33 

of  pleurococcus 339 

of  pollination  of  flowers  .     .     .  305 

of  protozoa 50,  53 

of  reptiles 135 

of  roots 271,  285,  404 

of  seed  dispersal 314 

of  seeds 263 

of  skeleton 188 

of  spirogyra 341 

of  sponge 59 

of  starfish 73 

of  stems 404 

of  tasting 166 

of  twigs 291 

of  wood 384 

of  worms 81 

of  yeast  plant 356 

Lacteals 174 

Lactic  acid,  effect  of   ...     .  348 

Ladybug 26 

eggs  of  (fig.) 26 

Lady  slipper  (figs.)      .    .      303,  397 


/  VDEX 


23 


Lampreys 

Land-locked  salmon,  eggs  <>i 

(fig.) 110 

Land  snail let 

Larch,  a  conifer 

Large  cells,  position  of  In  an- 
nual ring 286 

Large  intestine 168 

Lark,  meadow ill 

Larkspur,  medicinal  plant    .     .  327 

Larva,  o I  codling  moth  (fig.)    .  17 
of   mourning   cloak    butterfly 

(fig.)   •     .' 28 

Larvee.  of  bean  weevil  ....  316 

of  leaf  miner  in  elm  leaf  (fig.)  •  ;,,1 

Larynx 193 

voice  box  (fig.) 194 

Lateral  bud 288 

Lava,  change  to  soil     ....  100 

Lead,  cause  of  disease  ....  232 

Leaf,  buds  of  cherry  (fig.)      .     .  289 

epidermis  of  (fig.) 274 

of  elm  (fig.) •-".'! 

of  oak  (fig.) 294 

scars,  defined 289 

skeleton  (fig.) 273 

Leaflets,  of  compound  leaf    .     .  '-"-'J 

of  fern  frond 373 

Lean  meat,  example  of  protein  268 

Leather 1  •"»."> 

indirect  product  of  plants    .    .  401 

Leaves,  of  bean 260 

of  ferns '•  369 

of  grass,  shape  of 398 

of  ivy,  arrangement  of     .     .     .  398 

of  mosses 364 

of  pine,  described 378 

of  pitcher  plant  (fig.)  ....  390 

of  seed    .• 260 

of  trees,  arrangement  of .    •    .  398 

Leaves  and  bud  of  beech  ( fig.)  327 

Leech 76 

Leeuwenhoek,  improver  of  mi- 


//./.  /■•  no  i  ore  to  pagt  i 
.    .     106 


in     changing 


Hi  »sci  ipe 


:y>o 


Legs  and  wings  of  birds      .     •     136 

Lens  of  eye  (tig.) 216 

Lenticels.  described     ....    287 

Leopard  frog ill 

Lepidoptera 20 

Lianas,  defined 2W 


Lichens,     action 

lava  to  soil 

epiphj  tic  habit  of 

field  study  of 

(fig.) •.    .    .    . 

flection  -•:    ■         B1 

Life  history,  ol  tern  it: 

ol  grasshopper 15 

of  oyster,  Btagea  in  • :  _         .    .     101 

of  the  mosses  i  fig.  i      .    . 

of  the  plant,  defined    .    .    .* 
Life  processes it 

of  bacteria 

Light,  a  universal  stimulus    .     . 

a"  vital  condition 

Lilac,  yellow  swallowtail  butter- 
th     gathering    oectai    from 

(fig.) 

Lily  family 

Lily-of-the-valley  (fig.)  .     .     . 

Linden  twig  (fig.) 

Linen,  furnished  by  tfax  fami 

Bource  of  clothing i"l 

use  of  bacteria  ba  manufactur- 
ing   

Lingual  ribbon 

Linnseus,  work  of 

Lions 

Lipoid : 

Lips  of  frog 11"' 

Liver 117 

Liver  flukes 77 

Liverworts 7 

Lizards 131 

horned  toad,  example  of  •  I  g  129 
Lobes,  olfactory  ....        .lis 

optic  .     .     .     ' 119 

Lobster 

molted    eX.  .skeleton   of    I  fig.) 

Lockjaw 

Locomotion 

Locust 


Loggerhead  shrike  (fig  | 
Longitudinal  muscles 
Long-spurred  vude: 

-  of  sei            D 
Lumber,  from  gymnosperms 
t r<'iu  hardwood  trees 
furnished  bj  walnut  tan     j 
ho*  cut  


SO 


24 


INDEX 


References  are  to  pages 


Lumbering,  in  New  York  (fig.)  380 
operations,    forests    destroyed 

by 387 

Lungs 3,  117,  192,  193 

and  heart  (fig.) 193 

Luxuries,  fleshy  fruits      ...  311 

of  food  from  rose  family     .  328,  401 

Lymph 203 

Lymphatic  circulation  .     .     .  204 
Lymphatics,  superficial,  of  arm 

and  hand  (fig.) 204 

M 

Mackerel,  a  bony  fish  ....  106 

value  of,  as  food      .     .     .     ."  .  178 

Maggots,  larvae  of  flies     ...  19 

Magnesium,  a  salt 173 

Magnesium  sulphate  in  Pas- 
teur solution 356 

Main  arteries,  of  frog  (fig.)      .  202 

of  man  (fig.)  \ 203 

Malaria 42,  237 

caused  by  mosquito     ....  238 

protozoan  disease 234 

Malarial  parasite,  source  of    .  238 

Malarial  swamp  (fig.)      .     .     .  238 

Mallard  duck,  skeleton  of  (fig.)  138 

Mallow,  family,  importance  of  329 

flower  of  (fig.) 331 

Malt,  formation  of 355 

Mammals,  classified     ....  7 

discussed 150 

number  of 7 

report  on 155 

summary  of 159 

Man,  example  of  mammal      .     .  7 
Mandibles  (fig.)   ....    13,  14,  41 

Mantle 94 

Map,  of  corn  production    .     .     .  319 

of  cotton  production    ....  332 

of  potato  production    ....  335 

of  production  of  oats  ....  324 

of  production  of  orchard  fruits  330 

of  wheat  production    ....  325 

Maple,  seedlings,  cotyledons  of  .  282 
development  of  (fig.)    .      279,  280 

syrup 385 

trees,  products  of 385 

twig  (fig.) ,     .  289 


Maple  sugar  industry,  in  Ohio    385 

in  Vermont 385 

Marchantia  (fig.) 367 


Marsh  hawk,  partly  harmful  . 
Martins,  mosquitoes  eaten  by  . 
Massasauge,  a  rattlesnake  .  . 
Masts,  use  of  gymnosperms  for 
Material  for  clothing  .  .  . 
Matter,  organic  and  inorganic 


145 
42 
132 
384 
329 
9,10 
163 


Maturity,  a  period  of  life 
May    beetle,    injurious    insect 

(%•)   •    •    • 26 

May    flies,    member    of    order 

Ephemeridae 20 

Meadow  lark,  food  of      .     .     .  147 

nest  of 141 

Mealy  bug  (fig.) 25 

Measles,  probable  cause  of   .     .234 
Measuring      worms,      cater- 
pillars        19 

Meat 10 

indirect  product  of  plants    .     .  401 

lean,  use  of,  as  food    ....  176 
Mechanical  tissues  of  pteris 

stem 370 

Median  fins  of  fish 107 

Medicinal  members  of  crow- 
foot family,  list  of      .     .     .  327 
Medicines       furnished       by 

crowfoot  family   ....  327 

Medulla,  of  frog 119 

of  man 224 

Medullary  layer  of  kidney       .  207 
Medullary     rays,     in     woody 

stem 289 

of  pine 378 

Medullary  sheath  of  nerve      .  211 

Medusa,  described 67 

hydroid  (fig.)      .......  67 

pelagia  (fig.) 67 

Melons,  example  of  pepo  .     .     .  310 

Mendel,  Gregor,  study  of  peas  125 

Mendelian  laws,  defined      .     .  126 
Menhaden,    example    of    bony 

fish 106 

Mental     inefficiency,     cause 

of  poverty 257 

Mercury  poison .     .     .     .      221,232 

Mesentery  of  frog 117 

Mesoglea  of  coelenterate  .    .  63 


INDEX 


25 


Mesophyll  of  leaf 273 

Mesophytes.  ilfiiniiiuii  .,1'    .     .  397 

Mesothorax  of  grasshopper  16 
Metal   container   dangerous 

for  milk 300 

Metamorphosis 16 

complete 17 

incomplete 16 

Metathorax  of  grasshopper  16 

Metazoa,  defined 66 

Method   of  pollination,  basis 

of  classification •"-<>•"> 

Meyer.  Hans,  discovery  of  .     .  223 
Mice,  destroyed  by  hawks       145,  14<» 

harmful  mammals 166 

Microbes,  a  name  for  bacteria  .  343 
Microphotograph.      of     bone 

(fig.) L86 

of  brain  (fig.) 212 

of  conjugating  spirogyra  (fig.)  341 

of  corn  stem  (fig.) 279 

of  hydra  (fig.) o"'> 

of  stomach  (fig.) 170 

of  sun  flower  stem  (fig.)    .     .     .  286 

Micropyle,  of  bean 261 

use  of 300 

Microscope,  inventor  of  .     .     .  350 
Microscopic      animals      and 

plants 233 

Middle  ear  (tig.)  .     .     .     .      217,218 
Middle    West,    production    of 

corn  by 318 

Midrib  of  marchantia     .     .     .  367 

Migration  of  birds      ....  143 

Milk,  care  of 350 

card  of ,  example  of  protein     .  266 
from  healthy  cow  .  Dumber  of 

bacteria  in 347,  348 

good  and  bad  hottlinu  i  t'iL,r.)      .  362 

indirect  product  of  plants     .     .  101 

value  of,  as  food 178 

Milk   glands,  characteristic   of 

vertebrates 150 

Milk  teeth  (fig.) 166 

Milkweed,  fruit  (fig.)  ....  312 

plant  distributing  seeds  (fig  i  313 
Milkweed  butterfly    .... 

Milt  of  fish Ill 

Mineral  matter  in  food  ...  1 

Mineral  substances    ....  179 


on  to  j"i'/'  § 

Mink,  harmful  mammal    .    .    . 

Mint,  flower  ol  .... 

Mint  family,  charactei 
Mints  used  for  medic  ;d 

in  food 

Mistletoe,  absorbing  orgaus  ol 

a  Bemi-parasite    I 

branch  infected  \\  ith  (rig.)  . 
Mites,  arachnids 91 

parasitic 

Mixed  diet  of  man       ....     170 
Model,  dairj  cow  i  fig,  i     .    .     . 

dairy  stable  (fig  .     ,     .    248 

resen oir  (fig.)     .    .    .       .    .    'Jin 
Modified    cotyledon    (scutel- 

liu f  corn 

Modified  leaves,  of  club  m.>-> 

of  husks  of  corn 

of  |><-;i  plant  (fig.) 

Moisture,     a     condition      for 
growth  of  bacteria   ....    34  \ 

a  Bl  imulus 

a  vital  condition 315 

for  lichen  gathered  by  fungus  , 

Molars  of  man 167 

Mold,  grown  from  water  (fig  I 

Molds,  classified 7 

Moles  destroyed  by  hawkfl  .     \\'< 
Mollusca.  classified 

number  of 

MoUusks,  characteristics  of .    .      M 

life  history  of 

Bhells  of,  home  of  hermit  crab      91 

summary  of 1"'-' 

Molt,  defined 16 

Molting,  discussed 

Monarch  butterfly  (fig  |  20 

laboratory  b(  udy  of     .... 
Monkey,  example  of  mammal  .        7 
Monocotyledons,      group      of 
flowering  plants 7 

represented  bj  com 

Beeds  of . 
Monoecious  flower,  defined 

Of  beech  family    .... 

of  w  alnnt  famih 
Morning     glory,     a     climbli 
plan! 

a  dicotj  ledon 

sc.  (iiin--,  of US 


26 


INDEX 


References  are  to  pages 


Mosquitoes,  breeding  places     .  41 

members  of  Diptera  ....  20 

Moss,  composition  of  cushion  of  364 

two  generations  of 366 

Mosses,  and  their  allies    .     .     .  3(54 

classified 7 

general  features 364 

habitat 364 

life  history  of  (fig.)      ....  3(55 

number  of 7 

types  of  (fig.) 364 

Moths,  carriers  of  pollen  .     .     .  304 

example  of  Lepidoptera  ...  20 

Moths   and   butterflies,   field 

study  of 33 

Motile  cells  (sperms)  of  moss 

plants 365 

Motor  function 213 

Mourning"     cloak     butterfly 

(fig.) 29 

Mourning-  dove  (fig.)  ....  143 

Mouth,  cavity  of  earthworm      .  81 

of  man 164 

parts  of  grasshopper  (fig.)   .     .  14 

Movements  of  plants      .     .     .  392 

Mucus,  use  of,  by  clam     ...  96 

Mucous  membrane    ....  182 

Muscle,  bundle 188 

Muscle  cells,  heart  (fig.)      .     .  189 

involuntary  (fig.) 189 

voluntary  (fig.) 188 

Muscles,  color  of 188 

involuntary 188 

of  man    .     .     , 184 

of  upper  leg  (fig.) 188 

scars  of  clam 96 

voluntary 188 

Mushrooms,  edible  fungi      .     .  354 

poisonous 233 

Mustard,  a  common  plant  fam- 
ily .......     .     .323 

Mutton,  value  of,  as  food  .     .     . 

Muzzling  of  dogs 

Mya  arenaria,  edible  clam   .     . 

Myriapods,  discussed  .... 

Myrtle  warbler,  at  suet  station 


328 
178 
250 
100 
92 
148 


N 


Nails,  origin  of 190 

Narcotic,  defined 221 


Nasal  cavity  of  fish     ....  109 
Nasturtium,  twining  petiole  of 

(fig-) 292 

use  of  petioles  in 294 

Natural  gas,  formation  of    .     .  375 
Natural  laws,  basis  of  success 

in  agriculture 320 

Nectar,  relation  to  pollination 

by  butterfly 30 

sought  by  insects 297 

use  of,  to  flowers 389 

Needle-like  leaves  of  pine  377,  378 

Nephridia  of  earthworm  .     .  83 

Nereis,  an  annelid  worm  ...  84 

Nerve  cells  (fig.)      ....  209,  211 

of  mollusks 98 

Nerve  fibers,  defined  ....  209 

description  of 211 

gray  substance  of 211 

white  substance  of 211 

work  of 210 

Nerve  pathways  in  midbrain  119 

Nerve  trunk 222 

Nerves,  cranial,  of  frog    ...  119 

location  of 119,  210 

of  earthworm 82 

of  frog 118 

of  mollusks 98 

Nervous  system,  function  of, 

in  locomotion 2 

growth  of 211 

of  crayfish 90 

of    earthworm,   front    end   of 

(fig-) 82 

of  frog  (fig.) 118 

of  man  (fig.) 209,  210 

parts  of 209 

summary  of 230 

Nest,  of  bittern  (fig.)     ....  142 

of  chimney  swift  (,fig.)     .     .     .  144 

of  yellow  warbler  (fig.)  .     .     .  142 

Nest-building  of  birds    .     .     .  142 

Net-veined  leaf 272 

Nighthawks,      destroyers     of 

mosquitoes 42 

food  of 145 

Nightshade  family,  character- 
istics of        334 

Nissl  bodies 225 

Nitric  acid,  test  for  protein  .     .  265 


/  \  DEX 


27 


i:  /<  !■■  run  t 

Nitrogen,  a  chemical  element 

gathered  by  bacteria  .    .    .  270,  318 

in  lipoid 222 

proportion  of  In  living  thin.  '.• 

Node  of  corn  stem      ....  281 
Nomenclature  of  plants   by 

Linnseus 303 

Non-motile     cells    (eggs)     of 

moss  plants 366 

Non-productive  persons, 

Dumber  i>r 257 

Non-smokers,  scholarship  of    .  229 
Normal    body    temperature 

of  man 190 

Nose.  Bense  organ 215 

Notochord,    embryonic    struc- 
ture of  fishes   ....      103,  106 
Nourishment,  defined      .     .     .  1T."» 

in  beans 317 

Nuclei  of  pollen  and  egg-  (tiur.)  300 

Nucleoli  of  cells .". 

Nucleus,  of  cell 268 

of  nerve  cell 209 

of  pleurococcus 339 

Nurses,  care  of  bee  larva.*  by     .  :"><> 

Nuthatches,  at  snet  station      .  148 

at  hemp  ami  millet  station  .     .  I  1  ^ 

destroyers  of  Lepidopt era    .     .  '.1 

useful  birds Ill 

Nutrients,  defined 1 

Nuts,  from  hardwood  trees    .     . 

furnished  by  walnut  family  327 

indebiseent  fruits 310 

Nymphs  of  cicada  (fig.)      .     .  25 

O 

Oak,  leaf  (fig.) 294 

trees 327 

Oatmeal,  value  of  as  food     .     .  178 

Oats,  a  cereal  (fig.) 326 

a  monocotyledon 

map  of  production  of  .    .    .    .  324 

member  of  grass  lamik   .     .     .  326 

value  of  as  food 178 

Obelia,  classified 6 

microphotograpb  of  (fig.)    •     •  86 
Obnoxious  plants,  nanus  of    • 

Octopus,  example  of  mollusk  M 

member  of  cephalopoda  ( liu'-i  •  '•''•, 


Odonata.  order  of  .     . 

Odor,  use  "(  in  flowers 

Odors,  of  other  f Is  absorbed 

by  milk 

produced  bj  fermentation 

Oil,  tests  for 

Oils,  a  class  of  foods  .  . 
Old  agre.  a  period  in  lift-  li 
Olfactory  lobes,  function  ..f 

of  frog  (fig.) 

One-celled  plants  .  .  . 
Onions,  storage  •■!  food  in 
Operculum  of  fish  .  .  . 
Opium,  a  poison  .... 
Optic  lobes  oi  f p.-  nij  lis. 

Optic  nerve  di-.  i     .     .     .     .  21<>, 
Oral  side  of  starfish    .... 
Oranges,  a  form  of  fruit   .     .     . 

example  of  berry 

section  "i  | tii:  ) 

value  oi  as  i 1 

Orbits,  defined 

Orchard  fruits,  from  I  u- 

iiy 

mail  of  production  of  . 
Orchids,  greenhouse  epiphj 

pollinated  by  moths    .... 
Org-an.  defined 

pa it  1. 1'  body 

Organic  matter,  example  of 
Organism,  beginning  of  Den 

Btudj  "I 

Bensat ion  in 

Org-ans,  of  bean    ■     • 

of  circulation  (fig         .     . 

of  cia\  lish 

of  earthworm  (fig.  >     .    .    .    . 

of  frog  (figs.) 1 16, 

Of  plants 

Org-an  system,  defined     . 

part  "f  bod] 

Orioles,  food  of     ,     • 

nest  of    ...    . 
Orthoptera.  order  of  Insect! 

Osmometer   flg.) 

Osmosis,  defined  . 

bomemade  apparatus  for  show  - 
log  .... 

in  absorpt ion  »1  i 1 

in  photos)  uthcsit) 


l 
II  . 

IP' 

in; 

11'' 

JIT 

310 

213 


\ 
1" 

» 

M 
117 

t 

1 

142 


28 


INDEX 


References  are  to  pages 


Osmosis,  continued 

in  root  hairs 269 

in  sponges 58 

Outer  coat  of  pollen  grain     .  299 

Outer  ear  (fig.) 217,  218 

Outer  skeleton,  of  crayfish .     .  88 

of  turtle 130 

Ovary,  of  coelenterates      ...  68 

of  frog 118 

part  of  pistil 297 

Overwork,   predisposes  to   tu- 
berculosis      240 

Oviducts,  of  frog 118 

of  horned  toad 131 

Ovules,  change  to  seed      .     .     .  300 

described 297 

of  pine 379 

Owl,  feet  and  beak  of    ...     .  137 

screech  (fig.) 138 

snowy,  a  winter  visitant .     .     .  141 

Oxidation,  defined 1,  9 

in  birds 138 

Oxygen,  a  chemical  element      .  8 
a  condition  for  the  growth  of 

bacteria 344 

proportion  of,  in  living  things  8 

use  in  respiration 3 

use  of,  by  birds 138 

Oysters,  artificial  raising  of      .  100 
barnacles  and   clams  growing 

on  (fig.) 101 

destroyed  by  starfish  ....  74 

examples  of  mollusks  ....  94 

stages  in  life  history  of  (fig.)    .  101 

value  of,  as  food 178 


Pain 213,  215,  232 

Palate  of  man 166 

Palisade  cells  of  leaf  ....    272 
Panama  Canal,  a  health  prob- 
lem       239 

Pancreas 169, 172 

Pancreatic  juice,  enzymes  in  .     172 

Pansy,  capsule  of 310 

cleistogamous  flower  ....    302 
Paper,  made  from  spruce  trees  .    384 

Papillae  of  tongue 165 

Pappus,  use  of 389 


Paraffin,    in    transpiration    ex- 
periment       295 

Parallel  venation,  of  corn  leaf  282 
of  leaves  of  lily  family  .  .  .  326 
of  grass  leaves 323 

Paramoecium 6 

diagram  of  (fig.) 50 

example  of  ciliata 6 

mode  of  defense 51 

reproducing  by  fission  (fig.)  .  51 
resisting  attack  (fig.)  ....  51 
study  of 50 

Parasites,  action  of 233 

group  of  fungi 354 

ichneumons 30 

liver  fluke 77 

plants,  modifications  of   .     .     .     389 

tapeworms 76 

Thalessa 39 

Parasitism,  a  dependent  rela- 
tion       403 

Parsley  family,  characteristics 

of 331 

list  of  plants  in   .....     .     329 

Parsnips,    member    of    parsley 

family 

storage  of  food  in 

Partridge,  wings  of      .... 

Passer  domesticus,  scientific 
name  of  English  sparrow  .     . 

Pasteur,    discoverer    of    lactic 

acid  bacteria 

study  of  bacteria  by    ...     . 

Pasteurization,  denned   .     .     . 

Pasteurized  milk  tested  for 
bacteria 

Pasteur  solution,  formula  of  . 

Patent  medicines,  defined  .    . 
to  be  avoided  in  consumption  . 

Patrolling  of  forests  .... 

Paupers,  cost  of  supporting  .     . 

Pea  plant,  modified   leaves   of 

(fig.) 

member  of  bean  family    .     .     . 

seedlings  of 

Peaches   produced    by  rose 

family 329 

Peach-tree  borer 28 

Peanut,  peculiar  habit  of  (fig.)  .    318 
Peanut  shucks  as  adulterant    180 


329 
283 
136 


348 
350 
349 

347 
356 
244 

237 
387 
258 

294 

317 

282 


INDEX 


29 


Referenct  a 

Pears,  example  of  pome    .     .     .  310 

Pear  scab  (figs.) 359 

Peas,  Mendel's  experiments  <>n  .  125 

Pectoral  girdle  of  vertebrates  105 

Pedal  ganglion  of  clam      .     .  96 

Pelagia,  a  medusa  (fig.)    •     •    •  67 

Pelvic  girdle  of  vertebrates  106 

Pelvis,  of  kidney 207 

of  trunk  of  in;iii 207 

Penguins,  use  of  wings     .     .     .  136 

Pennaria,  classified ('» 

tiarella  (fig.) 68 

Pennyroyal,  a  medicine   .     .     .  331 

Peony,  use  of :<l'7 

Pepo,  special  form  of  berry   .    .  311 

Peppermint :;.".l 

Pepsin  in  gastric  juice  ...  171 

Peptone  in  agar-agar  formula  346 
Perch,  a  bony  fish  (fig.)    .       104,  106 

classified •; 

Perfect  flower,  definition  <>f     .  297 

Perianth  of  lily  family    .     .     .  326 

Pericardium,  of  clam  ....  97 

of  man 201 

Permanent  teeth  (fig.)    .     .     .  KIT 
Persian  lilacs  pollinated  by 

swallowtail  butterfly  (ti  v.)  299 
Perspiration,  amount    of,  how 

regulated L90 

a  waste  product        

use  of 190 

Petals  of  bean  flower     .         .  _".»*; 

Petiole,  length  of 389 

of  bean  leaf 272 

of  clematis  (fig.) '_".»_' 

of  nasturtium  (fig. )      .    .    .    .  '_".i2 

Petroleum,  format i f.     .     .  375 

Petunias,    members    of    night- 
shade family 331 

Phanerogams,  a  group  of  plants  c,  7 

Pharynx,  of  earthworm     ...  Bl 

of  man 164,  l»'»o 

Pheasant,  a  seed  eater      ...  1 17 

wings  of 1  •'••'» 

Phenolphthalein  test  for  acid  21  M ' 
Phlegmatic       temperament, 
heart  tracing  of  (fig.)    .     .     , 

Phloem,  carrier  of  food     .    .    •  271 

conducting  food  materials   •    .  '-"•',| 

constituent  of  green  bark          .  287 


are  to  pagi 
Phloem,  contintu  d 

pi  '-it  ion  in  w I\   -t .-m     . 

position  of  in  \  ascnlar  bundle 
Phaebes,  destroyers  "f  Lepidop- 

tera 

Photosynthesis,  finished  prod- 

net  of 

<-\ \ gen  produced  bj  .... 
performed  bj  stem  .... 
\  ital  process  In  plants 

Phosphates 176, 

Phosphorus,    a    chemical    ele- 


l 


menl  found  in  li\  ing  thing* 

a  poison 

in  lipoid 


179 


useful  in  body 

Phylum    (Phyla i    groups    of 

plants  and  animals  ...        7 
Physical  change  described    . 
Pieplant,  storage  <>i  food  in  .     . 

Pigment  in  skin 

Pigs,  important  mammals  151 

Pike,  a  bony  ti>h !<*; 

raised  in  hatcheries     .    .    .    .     ill 

Pill  bug  (fig.) 9] 

Pine,  example  of  gymnosperm   .       7 

pollen  of  (fig  I 57 

ripe  cone  of  i  fig. ) 

seed   Of    (  fig.) 

ataminate  Bl  robill  of  (fig.) 

t  ree,  described 77 

parts  of 

Pine     grosbeak    at    hemp    and 

millet  station n* 

Pine  siskin  at  hemp  and  millet 

station 148 

Pinnae  of  fern  frond    .... 

Pinnately  compound   leaves 

of  walnut  family  .... 

Pistil,  described 

diagram  of 

Pistillate  flower,  described 

of  monoecious  plant 

of  willow  (fig) 

Pitch,  souree  of     .     .     . 
Pitcher  plant 

leaves  ol  (fig  

use  of  leaves  In 

Pith  in  corn  stem       .... 
Plague  of  locusts    .... 


30 


INDEX 


References  are  to  pages 


Planarian  worm  (fig.)     .     .     76,  77 

Plant,  biology  .......  259 

cell  (fig.) 4 

conditions,  change  of  ...     .  400 

ecology,  definition  of  ...     .  399 

food,  of  interest  to  farmer  .     .  402 

lice 41 

injurious  to  corn  plant      .     .  316 

members  of  Hemiptera     .     .  24 

on  fern  (fig.) 24 

protected  by  ants     ....  41 

life,  mystery  of 404 

peculiarities  of 389 

or  animal  matter  food  of  bac- 
teria       344 

poison 233 

Plant-eating  animals      .     .     .  161 

Plant  societies 393 

Plant  succession 400 

Plantation    in    the     Adiron- 
dack^ (fig.)     ....      385, 386 
Planting-  young-  trees  in  the 

Adirondacks  (fig.)   ....  384 
Plants  as  organisms,  interest 

in 402 

Plants  decomposed  by  bac- 
teria    345 

Plasma 203 

Plecoptera,  order  of  insects      .  20 
Pleurococcus,    appearance    of 

(fig-) 338 

described 338 

example  of  alga 7 

group  of  cells 339 

where  found 338 

Plum,  example  of  drupe    .     .     .  310 

produced  by  rose  family       .     .  329 

Plumage,  discussed      ....  139 
Plumule,  connection  with  seed 

leaves 261 

defined 260 

part  of  embryo 301 

Pneumonia 234 

Pod  of  bean 260,  308 

Poison,  defined 221 

in  tobacco  smoke 230 

Poisonous  character,  of  crow- 
foot family 327 

of  lizards  —  Gila  monster  (fig.)  135 

of  snakes 132 


character, 


con- 


Poisonous 
tinned 

of  toxins 345 

of  plants  of  nightshade  family  331 

Pollen,  cell  (male  parent)      .     .  299 

distributed  by  wind      ....  305 

of  pine  (fig.) 387 

produced  by  stamens  ....  297 

sacs  of  pine 379 

tube,  formation  of 300 

of  pine 381 

Pollen        grains        growing 

through  pistil  (fig.)  ...  300 

Pollination,  by  wind     ....  305 

definition  of 297 

step  in  the  production  of  fruit .  308 

Pollution  of  -water     ....  247 
Polytrichum,  laboratory  study 

of 366 

Pome,  a  fleshy  fruit  (fig.)      .     .  309 

Pond  scum,  habitat  of     .     .     .  339 

Pome  fruits,  defined    ....  310 

Poppy,  capsule  of 310 

fruit  of  (fig.)   .......  308 

Pores  of  sponge 58 

Porifera,  classified 6 

Pork,  inspection  of 78 

trichinella  in 77 

value  of  as  food 178 

Posterior   adductor  muscle 

of  clam 95 

Potassium,  a  chemical  element 

found  in  living  things  ...  9 

contained  in  food 173 

Potassium  permanganate,  a 

disinfectant 253 

Potassium  phosphate,  in  Pas- 
teur solution 356 

Potato,    a    food    plant    of    the 

nightshade  family    ....  331 

(fig.) 285 

beetles,  injurious  insects      .     .  26 

blight,  a  fungus 360 

production,  map  of      ....  335 

response  of,  to  light    ....  393 

value  of,  as  food 178 

Poultry,   destroyed  by  certain 

hawks 145 

Preecocial  birds,  defined      .     .  143 

nest  of  bittern  (fig.)    ....  142 


/  VDEX 


31 


/,'  /<  r<  nces 

Prairie   dog's,    harmful    mam- 
mals      160 

Prairies,   suited   to    raising    <>f 

corn 318 

Praying-  mantids,  a  family  of 

Orthoptera Jit 

Predigested  foods,  use  of  .     .  181 
Pre-molar  teeth,  discussed  .     .  167 
Preparation     of    foods,    dis- 
cussed        177 

Preservatives,  list  of  .     .     .     .  348 

Preserved  substances  .    .     .  347 

Preventable  diseases  .  .  .  234 
Prevention,   of    communicable 

diseases '_'•">'. » 

of  plant  diseases 320 

Primary  root  of  bean     .     .     .  267 

Prisoners,  number  of  ...    .  257 

Proboscis  of  butterfly    .     .     .  29 

Propolis,  use  of,  by  bees  .  .  .  37 
Prop  roots  of  corn  (fig.)  278,  280 
Protective       coloration.      of 

birds 139 

of  grasshopper 14 

of  moth  (fig.) 33 

Proteid  substances  in  flour. 

source  of  food  for  yeast  plant  358 

Protein,  a  class  of  foods    .     .     .  169 

in  bean 317 

product  of  photosynthesis    .     .  276 

stored  by  beau *_'»i". 

Prothallium  of  fern,  a  gameto- 

pbyte 371 

Prothorax  of  grasshopper    .  Hi 

Protonema  of  moss  ....  : 165 
Protoplasm,  of  cell .     .     .     .     5,208 

of  pollen  grain :'><><) 

Protozoa,  cause  of  disease    .    .  237 

classified <"> 

flagellate  (fig.) 52 

number  of  kinds  of      ....  •'. 

resemblance  to  bacteria  .     .     .  343 

simplest  animals 15 

Protozoa  and  alcohol     .     .     . 

Protozoan  cell,  described     .     .  16 

Protozoan  culture  ....  19 
Psalterium,  division  of  stomach 

of  sheep  (fig.) 154 

Pseudopodium  of  amoeba  17 

Pteridophytes,  classified     .    •  7 


an  to  pugi 

Pteris,  described  (t  ... 

stein  (fig.) 

Ptomaines,  in  Ice  cream  .    . 
Public   institution 

tion  of  servants  for  .    .    .        244 
Puff   ball,    example   of    Coi 

(fig.) : 

Bpores  of,  "  Bmoke  " 

Puffins.  nest  of 142 

Pulmonary  tuberculosis,  dis- 
cussed       

Pulse,   caused    i>\    beating    ol 

heart 

Pulse,  members  of  bean  family, 
tnenl  loned  in  Bible  .... 
Pulse    family,    characterise 

of 

discussed      

foods  furnished  i>> 

li^t  of  plants  of 

\  alue  to  soil  of  plants  of      . 
Pumpkin,  example  of  pepo    ■    . 
Pumpkin  seed,  a  f i — 1  *  (fig.)  .     . 
Pupa,    a    Btage     in     metamor- 
phosis of  insects 

description  of 

of  cecropia  i  tiur.) 

of  codling  moth  (fig.)  .    •    •     • 
Pure  culture,  defined  .... 

Of  J  east 

Pure  food  laws 

Pure  milk,  cosl  of  producing 
Purple  finch,  at  hemp  and  mil- 
let station 1  18 

Purple  sea  urchin  .71 

Pyloric  valve  of  stomach  .     . 
Python,  a  constrictor   .... 


MX) 

311 
104 

18 
18 

18 

180 


Q 


Quack    defined       .... 

.    .    :\\ 

Quail,  a  seed  eater    .    .    . 

117 

at  w  hole  main  -.tat  ion 

149 

- — »  —  • 

Quarantine,  defined 

•.'17 

laws 

. 

violation  of 

2  17 

Queen  bee  (fig.)  .... 

d.  0 

1 

.    . 

32 


INDEX 


References  are  to  pages 


R 


Rabbits,  destroyed  by  hawks     . 

harmful  animals 

young  (fig.) 

Radial  arrangement  of  star- 
fish      

Radish,  a  dicotyledon    .... 

member  of  mustard  family  .     . 

roots  (fig.) 

storage  of  food  in 

Range    of   plant's   territory, 

how  increased 

Rank-scented  foliage  of 
nightshade  family    .     .     . 

Raphe  of  beans 

Raptores,  discussed      .... 
Raspberry,  in  plant  succession  . 

canes  killed  by  tree  crickets     . 

distribution  of 

produced  by  rose  family  .     .     . 

Rattlesnake,  a  poisonous  snake 

(fig.)         

discussed 

head  of  (fig) 

poison,  effect  of 

rattles  of  (fig.) 

Rats,  destroyed  by  hawks      .     . 

harmful  animals 

Raw  materials  of  photosyn- 
thesis      

Raw  milk,  danger  from     .     .     . 
Ray  flowers  of  composites    . 

Rays  of  starfish 

Rectum,     part      of     digestive 

system 

Red  bud,  member  of  pulse  fam- 

iiy 

Red  clover  pollinated  by 
bumble  bee 

Red  corpuscles  of  blood    .  197, 

Redheaded  woodpecker  (fig.) 

Red  poll,  at  hemp  and  millet 
station 

Red  rust  of  wheat,  a  fungus    . 

Red-shouldered  hawk   .     .    . 

Red-tailed  hawk 

young  of  (fig.) 

Red- winged  blackbird,  food 
of 


145 
155 
154 

71 

263 

328 
282 
283 

312 

334 
261 
140 
400 

22 
313 
329 

132 
132 
131 
233 
131 
145 
155 

276 
350 
334 

72 

168 

329 

304 

198 

28 

148 
360 
145 
145 
140 

22 


361 


Reflex  action,  discussed  . 

diagram  (fig.)      .... 

in  the  earthworm    .     .     . 

in  the  frog 

in  the  hydra 

Reforestation      .... 
Refrigeration  of  foods   . 
Regeneration,  defined 
Regular  flowers,  defined 

of  mustard  family  .     .     . 
Reindeer,  food  of     .    .    . 

useful  animal 

Relationships    of   plants    an 

interesting  study      .    .     . 

Remedies,  plants  a  source  of    . 

Report  on  twigs 

Reproduction,  a  life  process    . 

asexual,  defined 

of  amoeba 

of  bacteria 

of  grasshopper 

of  hydra 

of  paramcecium 

of  yeast  plant 

simplest  form  of 

Reproductive       bodies       of 

pteris 

Reproductive  glands  of  star- 
fish      

Reproductive      hyphse       of 

bread  mold 

Reptiles,  discussed 

life  history  of 

summary  of 

Reptilia,  classified 

number  of 

Reservoir,  model  (fig.)      .     .     . 

poor  (fig.) 

Resin,  source  of 

Respiration,  described      .     .     . 

artificial,  described      .     .     .     . 

in  man 

organs  of 

of  amoeba 

of  bean  plant 

of  grasshopper 

of  hydra 

of  mollusk 

of  paramoecium 

of  starfish 


212 

212 
214 
214 
214 
387 
240 
75 
302 
328 
,366 
154 

403 

401 

293 

2 

3 

49 

345 

15 

65 

51 

356 

339 

371 

72 

357 

129 

129 

135 

7 

7 

240 

241 

384 

2   3 

196 

192 

192 

49 

275 

15 

65 

97 

51 

74 


/  \  DEX 


li<  /■  n  n&  |  an  to  pa 


Respiration,  contimu  <> 

produces  carbonic  acid  gas  .         276 

studenl  report  <>n 192 

Respiration,   blood,   and   ex- 
cretion   192 

Rest,  effect  of,  in  consumption  ,    236 

necessity  for,  in  keeping  well  .    240 
Resting-  stage  (pupa)  of  cod- 
ling moth 19 

Restricted  diet  of  primitive 

life 170 

Reticulum,  division  of  stomach 

of  sheep  (fi^-) 164 

Retina  (fig.) 216 

Rhizoids,  of  marchantia    .    .    .    367 

of  mosses 364 

Rhizomes 286 

Rhizopoda,  classified  ....  6 
Rhododendrons,  insect  visitors  34 
Rhubarb   (pieplant)  storage  of 

food  in 293 

Ribbed      stems     of    parsley- 
family    331 

Rib  of  leaf 272 

Bice,  amount  produced  in  lr.  S. 

member  of  grass  family  .     .     . 

use  of,  in  China  and  India    .     . 

value  of,  as  food 

Right  shell  of  clam  (tiur.)      .     . 

Rind  of  corn  stem 281 

Ring   of  cambium  in  woody 

stems 287 

Ripe  cone  of  pine  (tiir-)  .  .  .  378 
Ripened  ovary,  the  fruit  of  a 

plant 308 

Robber  bees 36 

Robin,  a  useful  bird Ill 

food  of 27 

often  a  winter  resident  (tig.)    .    141 
Rochelle    salts    in    Fehling's 

solution 265 

Rock  oil,  formation  of .    .    •    •    375 

Rocks,  habitat  of  Lichens  .      .      .     360 

habitat  of  pleurococcufl   •     •    • 

Rod-shaped  bacteria      .     .     .  343 

Romans,  use  of  beans  b\  .  317 

Roots  of  ferns 369 

of  pine 

Rose,  a  common  plant  family     .  328 

compound  Leaves  of     ....  294 


326 

3-_'i ; 

326 

178 

95 


Rose,  continui  d 
family,  discussed    .... 
foods  furnished  by   ...     KM 

Mow  it  t  urning  into  a  fruit    I 

leaf,  stipule-,  ,d  (fig.)  .    . 
stamens  and  pistil  of  <uj.  I  . 
thorns  of  i  fig.)    ,     ,    . 
Rosebreasted     grosbeak,     it 

Buet  station 1 1  ^ 

desl  roj  er  of  potato  be< 

Rosette  of  moss  plant 
Rotating  crops,  reason  for 

Rootcap  (fig.) 

Roothairs,  of  bean  (fig.)   . 

uses  of 

Rootlets  of  bean 

m1  two  corn  plant*,  (fig.)  . 
Roots,  of  alfalfa  (fig  .      • 

of  bean 

of  beet  (fig.) 

Of  dahlia  (fig.) 

of  eiiibr\  0 301 

of  radish  (fig.) 

Rootstocks 

Root  system,  of  bean       .     . 

of  corn 280 

Round  clams 100 

Round  leaves  of  sundew    . 
Rudimentary  toes  of  cow 

Rules  of  hygiene 351 

Rumen,  division  of  stomach  of 

sheep  (fig.) 154 

Rushes  related  to  ferns     .     . 
Rye.  a  cereal  (fig.) 

a  monocotj  ledon 

member  ol  grass  familj 
Rye  bread,  value  of  as  f 1  178 


Sage,  a  member  ol    mint    family 

Sage  brush  |  ti-.i 

Sailing  birds,  examples  of    . 

wings  of 

Salamander,  p| 
discussed    I         ...  n  • 

Saliva,  us.-  of,  in  man    . 

of  mosquito 

Salivary  glands,  of  man. 
t  ion  of 

of  mosquito 


34 


INDEX 


References  are  to  pages 


Salmon,  example  of  bony  fish  . 

in  hatcheries 

landlocked,  eggs  of  (fig.)      .     . 

value  of  as  food 

Salt,  a  fundamental  taste       .     . 

common,  scientific  name  of 

use  of  in  preserving  meat     .     . 

Salt  rising  bread 

Salts  in  food 

Salvia  flower  (fig.)  .... 
Sand  swallow,  nest  of     .     .     . 

Sand  worm 

San  Jose  scale,    an    injurious 

insect       

Sap,  flow  of,  in  spring   .... 

Sap  conducted  laterally  by 

medullary  rays     .... 

Sap    tubes    affected    in    bean 

blight 

Saprophytes,  group  of  fungi  . 
Sardines,  example  of  bony  fish 
Savory,  member  of. mint  family 
Sawdust,  adulterant  .... 
Saw-fly,  horn-tailed  (fig.)  .  . 
Scale  insects,  spray  for  .  .  . 
Scale-like  leaves  of  cedar 

Scales,  of  fish  (fig.) 

modifications  of  skin  .  .  . 
Scales  of  staminate  cone  .  . 
Scallops,  edible  mollusks  .  . 
Scarlet  fever,  probable  cause  of 
Scars,  characteristic  of  stem 
Schiller  on  use  of  wine  .  . 
Scholarship,  effect  of  smoking 
on 

effect  of  drink  on  (fig.)    .     .     . 

Sclera 

Sclerotic  coat  (fig.)  .... 
Scorpions,  example  of  Arach- 

nida 

Scouring  rush 

Screech  owl,  a  useful  bird  .    . 

adult  (fig.) 

at  suet  station 

Scutellum,  digestive  organ   of 
corn  grain    ....   262,  266, 

Scutes  of  snake 

Scyphozoa,  classified  .... 
Sea-anemone,  described .     .     . 

member  of  coelenterates  .     .     . 


106 
111 
110 
178 
165 
173 
347 
179 
173 
306 
142 
84 

24 

291 

291 


315 
354 
106 
331 
180 
40 
25 
383 
107 
190 
379 
100 
234 
286 
220 

229 
221 
215 
216 

91 
374 
145 
138 
148 

280 

131 

6 

68 

63 


Sea-cucumber,  member  of 
coelenterates 

Sea-fans,  described 

member  of  coelenterates  .     .     . 

Sea-lily,  member  of  coelenter- 
ates (fig.) 71 

Sealing,  object  of 

Sea-lions  (fig.) 

Sea-plumes,  described      .     .     . 

Sea-turtle  (fig.) 

Sea-urchins,  classified  .  .  . 
members  of  echinoderms  (fig.)  71 

Sea-weed,  removal  of  from 
oyster  beds 

Sea-worm  a  true  worm     .     . 

Secondary  roots  of  bean  .     . 

Secretions  of  sundew,  use  of 

Sectional  view  of  branch  in- 
fected with  mistletoe  (fig.)  • 

Section  through  scab  of  pear 

(tig-) 

Seed,  development  of    ...     . 

distribution  of 

of  pine  (fig.) 

of  strawberry 

Seed-bearing  plants,  a  group 
of  plants 

trees  

Seed  bud  (plumule)      .... 

connection  with  seed  leaves 

Seed  coat  (testa) 

Seed  distribution 

Seed-eating  birds  .     .     .      147, 

bill  of 

claws  of 

Seed  leaves,  connection   with 

seed  bud 

Seedless  plants,  a  group    of 

plants      

Seedlings,  honey  locust  (fig.)    . 

horsechestnut  (fig.)      .... 

maple  (figs.)    .....      279, 

wheat  (fig.) 

Seed-producing    organs     of 

pine 

Seeds,  of  berries 

changes  in  size  made  by  cross 
fertilization 

devices  for  distributing   .     .     . 

food  of  birds 


71 
69 
63 

,74 
347 
153 
69 
129 
6 
,74 

74 

84 

267 

390 

399 


359 
301 
311 
387 
310 

7 
377 
260 
261 
260 
311 
148 
137 
137 

261 

7 
281 
281 

280 
282 

379 
310 

311 

336 
148 


INDEX 


R(  u  /■<  noes 

Seeds,  continued 

of  cotton  ( fig.  | 313 

of  weeds      

Selaginella  (tig.) ;,7} 

member  of  tern  group ....  373 

Selection,  effect  on  wild  plants  320 

Self-heal  (fig.) ;;;;;; 

Self-pollination,  discussed    .    .  306 

prevention  of 306 

Semi-circular  canals  of  ear   .  218 

Sensation,  a  life  process   ...  2 

Sense  organs,  list  of    ...    .  _'ir. 

of  touch,  locution  of     ...     .  190 

Senses,  use  of       2 

Sensory  function  of  afferent 

nerves 213 

Sepals,  described 296 

Sepia,  described 100 

Septic  sore  throat,  epidemic  <»f 

(fig.) 243 

Serrate  edge  of  leaf  of   Rose 

family 328 

Seta  of  moss  sporophyte    .     .  366 
Setae  of  earthworm    ....  B0 
Seventeen    year    locust    (ci- 
cada)    

Severe  cold,  effect  of  on  plants  396 

Sewage,  improper  can- of     .     .  'JIT 
Sexual  reproduction  .... 

of  hydra 66 

of  spirogyra 341 

Sexual  spore :;ii 

Shad,  example  of  bony  tisli    .     .  Hx; 

raised  in  hatcheries     .     .    .     .  Ill 
Shaggy  cap  or  cover  of  moss 

capsule :^;i 

Shape  and  size  of  bacteria  343 

Sharks,  a  division  of  fishes    ,     .  106 
Sharp-shinned   hawk,    partly 

harmful 146 

Sheep,  economic  value  of        154,166 

example  of  mammal    ....  7 

fed  on  beans 316 

stomach  of  (fig.) 164 

Shell  of  slug 99 

Shells  of  snail  (liii)      ....  99 
Shrews  destroyed  by  hawks  l  \:> 
Shrike  (great  northern),  a  win- 
ter visitant Ill 

loggerhead  (tig.) 139 


ill'i     tO  /nil/'  s 

Shrimp.s,  economic  Importai 

of 

Sickness,  student  report  on  . 
Sieve  vessels  of  phlotfm 

use  <d 

Silica  in  skeleton  of  sponge         61 
Silique    of    mustard  ly 

(fruit  i 

Silk  of  corn,  attachment  of 

t  he  Btyle 

Silkworm,  a  beneficial  insect    . 
Simple  leaf  (fig.) 

of  beech  family 

defined 

Sinus,  defined 

Siphonaptera,  an  order  ol    ln« 

sects 20 

Siphons  of  clams  Mi_. i     .     . 
Siphons  of  soft-shell-  rn 

(fig.) 100 

Skating,  good  exercise  .     .     . 
Skeletal   structures,    student 

report  on 187 

Skeleton,  external,  of  corals 

of  crayfish 

of  dog  (fig.) ; 

of  fish  (fig.) I 

of  leal  (fig.) 

Of  mallard  duck  (fig  |  .      .      .      . 

Of  man  (fig.) 184 

summary  ol     ....  r«> 

of  protozos 

of  sponges  (fig.) .    .    •  "■'•.  'd 

Skill  and  endurance  ii:  >d 

by  drink  (fig.) 

Skin,  as  sense  organ  ... 

described .    216 

diagram  of  (fig.) 

example  i  in 

of  fruit 

Skunk,     example     of     harmful 

mammal  ( ti^.i  .     . 
Sleep,  amount  needed    .     . 
Sleeping  sickness   how  »pn  id 

probable  cause  of  .  .  . 
Slimy  feeling  of  spirot  • 
Slimy    substunc.  |    ipoo 

r<  nio\  ed  h\   b 
Blips  producing 

roots '"1 


36 


INDEX 


References  are  to  pages 


Slug-  (garden)        

Slugs,  examples  of  mollusks 
Small  cells,  position  of  in  annual 


99 
94 

290 
116 
168 
251 
250 
234 
14 


Small  intestine,  of  frog    .    .     . 

of  man 

Smallpox,  Jenner  and  .... 
lessened  by  vaccination   .     .     . 

probable  cause  of 

Smell,  organ  of,  in  grasshopper 
Smoke,     result      of     chemical 

change     9 

of  puffball 364 

Smoker's  heart,  how  affected  .  227 
Smoking,  charts  showing  effect 

of 228,  229 

Smoking  and  scholarship  .     .  229 

Smoking  of  meat,  purpose  of  .  347 

Snails,  discussed 98 

example  of  Gastropoda  (fig.)  6,  98 
examples  of  mollusks  .     .     .     .  6,  94 

respiration  in 99 

shells  (fig.) 99 

tongue  of  (fig.) 98 

Snakes,  (black,)  harmful  .     .     .  132 

discussed 131 

examples  of  Reptilia    ...     7,  129 

food  of 132 

Sneezing,  distribution  of  germs 

by 197 

Snowy    owl    a    winter   visi- 
tant      141 

Soda,  a  nutrient 176 

preservative 348 

Sodium  carbonate  in  artifi- 
cial pancreatic  juice    .     .  173 
Sodium     chloride,      scientific 

name  for  common  salt  .     .     .  173 

Soft  palate  of  man      ....  166 
Soft-shelled    clam,   an    edible 

mollusk  (fig.) 100 

discussed 100 

Soft-shelled  crab  (fig.)     ...  91 
Soil,  an    element  of  success  in 

agriculture 320 

upper  layers,  habitat  of  bacteria  344 

Soil  bacteria  (fig.)    ......  344 

Soldiers,  a  class  of  ants     ...  41 
Soles  of  feet,  animals  that  walk 

on 152 


Solomon's  seal,  stems  of      .     .  285 
Song   sparrow,   at   hemp  and 

millet  station 148 

killed  by  hawks 145 

useful  bird 144 

Sori,  of  ferns  (figs.)  .     .     .     .370,371 

Sorus,  position  of  (fig.)      .     .     .  372 

section  of  (fig.) 372 

Sounds  from  sound  waves    .  218 
Sour,  a  fundamental  taste     .     .  165 
Source  of  man's  food  sup- 
ply        320 

Sources  of  danger  in  milk     .  349 
Souring  of  milk,  cause  of     .  348, 350 

Sparrow,  chipping,  useful  bird  144 
English,  chatter  attracts  other 

birds 148 

example  of  bird 7 

fox,  example  of  transient  bird  141 
hawk,     destroyer      of     grass- 
hoppers       22 

destroyer  of  cicadas      ...  26 

Sparrows,  seed-eaters  ....  148 

Spawn,  migrations  of  fishes  to  109 
Spearmint,    member    of    mint 

family 331 

Special      modifications      of 

plants 389 

Special  senses,  organs  of     .     .  215 
Species  defined  by  Linnaeus  303 
Specific  names  used  by  Lin- 
naeus    303 

Sperm,  a  sexual  cell 4 

cells  of  fern 371 

of  moss  plant 365 

volvox 56 

nucleus  of  pollen  grains  .     .     .  299 

Spermaries  of  hydroids     .     .  68 
Sphinx    moth   from    tomato 

worm     ........  34 

Spicules,  described  (fig.)  ...  59 
Spider,   member  of    Arachnida 

(fig.) 91,92 

Spinal  column  of  man,  curves 

of 187 

Spinal   cord,   part  of   nervous 

system 119 

Spines  of  echinoderms  ...  71 

Spiracles,  location  of    ...     .  16 

of  grasshopper     ......  15 


/  \  DEX 


Spiral  arrangement  of  scales 

on  cones 379 

Spiral  bands  of  chlorophyll 

in  spirogyra 310 

Spirillum,  a  form  of  bacterium  343 
Spirogyra,  example  of  algae      7. 

conjugating  (fig.) 340 

described 339 

microphotograph  of  (fig.)    .    .  341 
Spirog-yra  and  pleurococcus, 

summary  of 342 

Sponges,  bath  (fig.)      ....  58 

classified 6 

clog  water  mains (>1 

described .".7 

economic  importance  of  .     .     .  r,i 

example  of  Porifera     ....  »i 

how  gathered 61 

how  prepared 61 

number  of 6 

parts  of  (fig.) 59 

relation  to  other  animals      .     .  til 

reproduction <K> 

structure  of 58 

summary  of 62 

two  stages  in  development   of 

(fig.) 60 

use  of  bacteria  in  preparation  of  .'^.". 

where  obtained <>1 

Spongilla,  reproduction  of     .     .  60 

Spongy  layer  of  leaf  ....  27:; 

tissue  of  velamens 399 

Spleen,  of  frog 117 

Splints,  used  in  Betting  bones  186 

Spoiling  of  food  by  bacteria .  347 

Sporangia,  of  pteris  (fig.)      .     .  .".71 

Sporangium,  of  club  moss  (fig.)  373 

Spores  (tig.) 360 

of  bread  mold 357 

of  (dub  moss  (  fig. ) 373 

of  corn  smut  (fig.) 362 

of  moss 364 

Sporophyte,  dependence  of  .     .  366 

generation  of  moss 366 

Sprain,  defined 186 

Spraying  solution,  ingredients 

of 25 

outfit  (fig.) 21 

Sprouting  of  grain  to  furnish 

malt 355 


an  to  i ""/>'* 

Spruce,  compared  with  pine 
•  cample  ol  l:>  mnosperm 
t iii'-  source  "i  vrood  pulp 
wood  of  (fig.) 

Sputum,  destructi 1    m 

<\\ 

Bpread  of  t  uberculo« 

Squarr     -I'msof  mint  family 

Squash,  a  dicotyledon  .    .         . 

example  ol  j  »*  -  j  *•  • 

d  (fig.) 

Squid,  described 

example  of  ( lepbalopoda 

of  niullnsk 

Squirrel,  agents   in    plant   dis- 
persal   

flying  (fig.) 

gray  (fig.) 

Stagnant  pool,  breeding  place 

for  mosquitoes 

Stalk  of  grain  of  corn  .  .  . 
Stamen,  diagram  of  .  .  .  . 
Stamens  and  pistils  of  | 

(fig.) 

Staminate  cones  of  pine      .     . 

Staminate  flower 

of  monoecious  plants    .... 

Ol    willow    (  tiur- ) 

Staminate  strobili.  ol  pirn       77 
Starch,  a  nutrient 

chemical  composition  of  ■ 

form  of  carbohydrate  .... 

in  fermentation  .    .    . 

in  floor 

product  "f  photosj  ni  bests 
Starfish,  anatomj  ol  (fig.  I 

body  "t".  diagram    .... 

classified 

described  (fig.)        •    • 

familj 

group 

internal  struct  are  of 
life  bistorj  of      ... 

looomol  ion  of  .     .     .     . 
•-n miliary  of     ... 

State   governments,    pi 

tion  ni  fires  bj 
Statistics   of  life   Insurance 

companies     .     . 
Steam,  a  form  of  water 


i 


311 


152 
151 


11 


1 
17'' 


71 

71 
71 


38 


INDEX 


References  are  to  pages 


Steam  heating  (fig.)    .     .      195,  197 

Steering",  use  of  fins  for    .     .     .  107 

Stegomyia,  a  mosquito    ...  42 

Stem,  of  bean 260 

of  corn  (fig.) 280 

of  ferns 369 

of  mosses 364 

of  pteris  (fig.)       ....      369,  370 

of  xerophytes,  green  color  of    .  396 

woody  (fig.) 289 

Sterile,  defined 347 

Sterile  hairs,  of  moss  plants     .  365 
Sterilized  -water  in  tests  for 

bacteria 347 

Sternum,  keeled,  of  birds      .     .  138 

Sticklebacks,  nests  of  ...     .  112 

Stigma,  part  of  pistil    ....  297 

featbery 305 

Stimulant,  craving  for      ...  226 

Stimuli,  causing  movement    .     .  392 

list  of 2 

Stinging-  cells  of  coelenterates  64 

Sting  of  bee .'    .  36 

Stipe,  of  fern 373 

Stipules,  of  pulse  family  .     .     .  329 

of  rose  leaf  (fig.) 331 

Stomach,  a  digestive  organ  .     .  2 

example  of  organ 5 

microphotograpb  of     ...     .  170 

of  sbeep  (fig.) 154 

of    starfish,    use    of    in    food- 
taking      73 

pear-sbaped  (fig.) 168 

valves  of 168 

Stomach-intestine  of  earth- 
worm       81 

Stomata,  entrance  of  bacteria 

tbrougb 315 

number  of 274 

in  xeropbytes 396 

of  fern 373 

of  leaf 273 

position  of  in  waterlilies  .      274,  394 

size  of 274 

Stonefhes,  members  of  Plecop- 

tera 20 

Stone  fruits,  defined    ....  310 

Stone  of  drupe 310 

Stones,  inorganic  matter  ...  10 

wet  by  spray  habitat  of  mosses  364 


Storage  of  food  in  leaves  .    .  293 
Straight-veined     leaves     of 

beech  family 327 

Stramonium,  a  medicine,  source 

of 331 

Strawberry,  description  of  .     .  310 

produced  by  rose  family  .     .     .  329 

value  of  as  food 178 

Street  cleaning  by  flushing, 

advantage  of 235 

String  beans,  canning  of  .     .    .  317 

ovules  in 309 

value  of  as  food 317 

Strobili,  of  pine 379 

staminate  (fig.) 377 

Structural  changes  due   to 

alcohol 225 

Structure  of  amoeba     ....  47 

of  paramoeciurn 50 

of  roots 267 

of  woody  stems 287 

Struggle    for  existence,  dis- 
cussed        314 

modifications  aiding  in    .     .     .  389 

Student  report,  on  sickness     .  232 

on  skeletal  structures      .     .     .  187 

on  water  supply 242 

Studies   about   plants,  kinds 

of 311 

Study  of  lichens,  field  trip  for  362 

Study  of  plants  as  organisms  .  320 

Style,  part  of  pistil 297 

Success  in  cultivating  plants  320 

Sucking  disks  of  starfish  .     .  73 

Suction  in  photosynthesis     .  276 

Suet,  for  winter  feeding  of  birds  148 

station 148 

Suet-eating  birds 148 

Suffocation  discussed    .     .     .  196 

Sugar,  a  nutrient 1 

broken  up  by  yeast  enzyme      .  354 

elements  in 9 

form  of  carbohydrate  ....  265 

in  flour 179 

obtained  from  maple  trees  .     .  385 

organic  matter 10 

product  of  photosynthesis    .     .  276 

solution  in  study  of  spirogyra  341 

source  of 400 

value  of  as  food 178 


INDEX 


Re/i  n  in-'  $ 

Sugars  formed  in  fermenta- 
tion       365 

Sulphur,  a  disinfectant      .     .     .  253 

an  elemenl  in  living  things  .     .  9 

in  spraying  solul  Ion     ....  25 

Summary,  of  amphibians     .    .  127 

arthropods 93 

bacteria ."..".1 

bean 320 

birds 149 

circulation jus 

con  iters 388 

corn 321 

digestion  of  man l*'j 

disease 258 

ferns  and  their  allies   ....  375 

fish 112 

flowering  plants 336 

fungi :;•;_' 

hydra-like  animals 7<» 

insects 4.1 

mammals 159 

mollusks KL' 

mosses  and  their  allies     .     .     .  368 

nervous  system '_':!<> 

of  our  interest  in  plants  .     .     .  40i 

protozoa 54 

reptiles 135 

simplest  plants 339 

skeleton  of  man l'.»<> 

spirogyra  and  pleurococcus      .  342 

sponges 62 

starfish  group 75 

worm  group 84 

Summer  residents,  examples 

of ill 

Sundew,  described 390 

diagram  of  (rig.) ."-'.'1 

photograph  of  (tig.)      ....  390 

rapid  movements  of     .     •     .     .  392 

sticky  substance  on  leaves       .  390 

use  of  leaves  in 294 

Sunflsh,  care  of  eggs  by    .    .    .  112 
example  of  bony  tish  (fig.)     104,  106 

Sunflower,  "  seed  "  (I'm. )       .     .  262 

stem,  microphotograpb  of  i  fig.)  286 

Superficial     lymphatics     of 

arm  and  hand  (tie,.)   .     ■     .  204 

Supply   of  oxygen   kept   up 

by  plants I'd 


t<>  pagy 

'  Surplus  food  stored  in  ro> 
'  Survival  of  the  fitter 
Swallows,  destroj 

insects 

Swallow-tail    b>.  pol- 

linating Persian  til 

from  celerj  \\  orms 

la  rvaa  of 

Swamp,  breeding  place  for  i 

quitoes  (fig.) 

Swarming  of  bees       .... 
Sweat  glands,  location  of    .     , 

number  of 

work  of 

Sweet,  a  fundamental  taste  .     . 
Sweet  pea.  flower  of  (1 
Swifts,  destroyers  of  flying  bi- 
sects     

Symbiosis,  a  dependent  relation 

defined 

example  of 

Symptoms,  medicines   in  con- 
ned ion  with 


314 


190 
165 

i « 

361 
61 

245 


Tachina  fly.  beneficial  Insect 
Tadpole,   development  of  from 



two  stages  in  (fig.)   .... 
respiration  of  by  gills  .... 

Btage  of  frog 

Tail  region  of  flsh 

Talons,  characteristic  <»f  birds 
of  prey    

Tanning,  use  of  hemlock  hark  in 

Tap  root  of  bean 

Tapeworm,  a  common  (fig.) 

classified 

Tar.  source  of 

Tarsus  of  grasshopper's  foot 
Tartar,  effect  on  gums  .... 
Tassel,  staminate  flower  ol  corn 

Taste  cells  (fig.) 

Technical  names  of  of 

flower 

Teeth,  milk  (fig.)      •     • 

ol  man 

permanent  (fig.) 

Telegraph  poles,  use  of  gyTOr 
oosperms  for 


n 
122 

122 
106 

in 

78 

<■ 

16 
167 


166 
II  I 
167 

•N| 


40 


INDEX 


References  are  to  pages 


Temperament,  excitable,  heart 

tracings  of  (fig.) 228 

phlegmatic,  heart  tracings  of 

(fig.) 228 

Temperate     regions     as     a 

habitat 161 

of  evergreens 381 

Temperature 

of  birds 138 

offish 109 

of  soil,  an  element  of  success 

in  agriculture 320 

Tendrils  of  pea  plant  (fig.)    .     .  291 

response  of  to  contact      .     .     .  393 

Tent  caterpillar 28 

Tentacles  of  hydra     ....  64 

Terminal  bud 288 

cones  in  relation  to      ....  379 
Terrapin,  use  of  as  food    .     .     .  131 
Testa    developed    from    in- 
tegument    301 

Test  for  oxygen 8 

Test  for  weevils 316 

Tests  for  foodstuffs 265 

in  baking  and  brewing     .     .     .  356 

Thalamencephalon  of  frog    .  120 

Thalessa,  larva  of 40 

Thallophytes,  classified   ...  7 
Thallus  of  marchantia   .     .     .  367 
Thick  stems  for  food   stor- 
age       285 

Thick- -walled  cells  of  annual 

ring,  how  formed     ....  290 

Thigmotropism,  defined      .     .  284 

in  climbing  plants 287 

in  roots       284 

Thin- walled        cells,        when 

formed 377 

Thirty  years  of  diphtheria  in 

N.  Y.  State  (fig.)     ....  242 

Thistle,  a  common  weed    .     .     .  334 

Thoracic  cavity 201 

Thoracic  duct 174 

Thorax,  of  grasshopper     ...  13 

Thorn,  modified  leaf  (fig.)     .     .  293 

Thorns  of  rose  (fig.)     ....  329 
Thousand-legged         worms 

(fig.) 92,  93 

Thread-like   hairs,  of   spirilla 

and  bacilli 343 


Threads,  of  bread  mold     ...    357 
of  spirogyra    .     .     .  * .     .     .     .    340 

Throat,  cavity  of  man  .     .      164,  166 
of  tadpole 122 

Thyme,    a    member    of     mint 

family 331 


16 
43 
91 

155 


30 
153 
263 
331 

34 


Tibia,  of  grasshopper     .     .     . 
Ticks,  harmful  insects  .     .     . 

members  of  Araehnida  .  . 
Tigers,  harmful  animals  .  . 
Timbers  of  mines,  use  of  gym- 

nosperms  for 384 

Tissue 4,  5 

definition  of 268 

Toad,  horned  (fig.) 129 

Toads,  hibernation  of  ....  123 
Toadstools,  example  of  fungi  .  7 
Tobacco,   aroma  of,    produced 

by  bacteria 345 

effects  of  use  of 226 

inhaling  fumes 229 

member  of  nightshade  family  .    331 
Tobacco    worm,    bearing    co- 
coons of  parasite  (fig)  .     .     . 
Toes  of  cow,  rudimentary    .     . 
Tomato,  a  dicotyledon       .     .     . 

food  plant  of  nightshade  family 

worms,  larvae  of  sphinx  moth  , 
Tongue,  a  sense  organ  (fig.)  165,  215 

of  man 164 

of  snail  (fig.) 98 

Toothache,  result  of  poor  teeth  167 
Tortoise,  use  of  as  food  ...  131 
Touch,  movement  caused  by      .    392 

skin,  an  organ  of 215 

Toxin,  bacterial  poison      .     .     .    351 

of  diphtheria 252 

secreted  by  bacteria    ....    345 
Trachea,  of  man 192 

of  grasshopper 15 

Trailing      arbutus,      creeping 

stem  of  (fig.) 

Transformation    of   pupa   of 
mourning  cloak  butterfly 
into  adult  (fig.)  .... 
Transient  birds,  examples  of 
Transpiration,  defined     .     . 

devices  for  retarding  .     .     . 

experiment  to  show     .     .     . 

in  full  grown  leaves     .    .     . 


288 


29 
141 
274 
397 
295 
291 


INDEX 


11 


Trap-like  device  of  Venus's 

fly-trap 39] 

Tree  cricket,  incomplete  meta- 
morphosis <>|  (fig.)      ...  17 

harm !ul  insect 22 

Tree  frog  (fig.) 126 

Tree  killed   by  bracket  fun- 
gus (fig.) 369 

Tree  sparrow  at  bread  crumb 

station Ms 

at  suet  station Ms 

Trees,  habitat  of  lichens    .    .    .  360 

life  processes  of 259 

Tremex  borer,  harmful  insect  •  40 
Triangular    flaps,    mouth    of 

clam «x; 

Trichina,  discussed 77 

Trichinella,  discussed  (fig.)  .    77.  7^ 

Trichinosis,  cause  of    ...     .  7H 

Trichocysts  of  paramoecium  60 

Tropical  vegetation  (fig.)    .     .  4<  >1 

Tropics,  as  a  habitat     ....  161 

home  of  epiphytes 399 

Trout,  example  of  fish  ....  »i 

bony  fish 106 

True  flowering  plants     .     .     .  323 

Trunk  region  of  flsh  .     .     .     .  l<x; 

Trunks  of  evergreens     .     .     .  :;77 
Tsetse    fly,    sleeping    sickness 

spread  by 239 

Tubercles,    on    roots    of    bean 

family 270 

Tuberculin  test,  for  cows    .     .  349 

invented  by  Koch 361 

Tuberculosis,    a    bacterial    dis- 
ease        197 

cure,  summer  (fig.)       ....  236 

winter  (fig.) 237 

discussed 236 

in  cows 349 

of  throat  and  other  organs  .     .  237 

persons  affected 240 

Tubular  appendages  of  male 

crayfish ^7 

Tubules,  of  kidney 207 

Turgid  cells J7."> 

Turnip,    member    of    mustard 

family 

storage  of  food  in 283 

Value  of  as  food 178 


an  to  /""/'  s 

Turpentine,  source  of  ...    . 

Turtle,  example  ol  Reptllia       7.  129 

green,  use  of  as  1 1    .  13] 

skeleton  of 190 

Turtles,  discussed 130 

Twining    petiole,  of   clemal 
(fig.)     .     .  ... 

Ol  nast  urt  mm  (fig.)  . 

Twining  plants,  direction  of 
curve  of 

Twining  stem  of  dodder 
(fig.) 

Twining  stems 

Two-parted   flower  of    mint 

(fig.) 

Tympanic  cavity 

Tympanic  membrane     .     . 
Types,  of  mosses  I  fig.  I      .    . 

of  twigs  (fig.) 

Typhoid  fever,  a  bacterial  <li: 

ease 

spread  by  carriers 

Typical  fern,  pteris  .... 
Typical  flowering  plant,  bean 
a 


U 


Ulmus  americana 7 

Umbel 

Umbrella-shaped      branches 

of  marchantia 

Underground  stems,  de-crih..  I 

examples  ol 

of  pteris 

Undissolved  food 17} 

Unhealthy  cows,  milk  tr.'in 
Unicellular    fundus.   yeasl    an 


example 


Univalves 

Universal    stimuli   of    plants 

Unusual  plants 

Unwashed   hands,  number  <>f 

bacteria  on      

Ureter,  of  frog 1  17 

ol  man 2tfi 

Urethra,  of  man 

Urine,  defined       •  308 

Urinary  bladder  of  frog  117 

Useful  birds.  .\. in..  Ml 


42 


INDEX 


References  are  to  pages 


Vaccination,  discussed     .     .     . 
Vacuole,  food,  of  amoeba      .     . 

contractile 

Vacuoles,  in  nerve  cells    .     .     . 
Valves  of  arteries  and  veins  .     . 

of  stomach 

Vapor,  a  form  of  water  .  .  . 
Variations  in  legs  of  birds  . 
Varied  diet  of  man  .... 
Various  forms  of  cells  in 
human  body  (fig.)  .  .  . 
Vascular  bundles,  formation 

of  tubes  by 

of  root 

of  woody  stems 

Vascular  system  in  plants  .     . 
Vase-like  leaves  of  pitcher 

plant 

Vaseline,  use  of  in  transpira- 
tion experiment 

Vase-shaped    organs    (arche- 

gonia)  of  moss 

Vedalia,  beneficial  beetle      .     . 
Vegetable  food,  highest  form 

of 

Vegetable  forms  of  protein 
cheaper  than  meat  .     .     . 
Vegetable  nitrogen,  source  of 
Vegetables,  new  varieties  pro- 
duced by  cross-pollination     . 

food  of  man 

Veins,    compared    with    fibro- 
vascular  bundles      .... 

diagram  of  (fig.) 

of  leaf 268, 

of  man 

of  the  leaf  of  pteris  (fig.)      .     . 

of  wing  of  insect 

Velamens 

Ventilation 

room  at  night,  direct  heating 

(fig.) 

indirect  heating  (fig.)    .     .     . 
room  in  daytime,  direct  heat- 
ing (fig.) 

indirect  heating  (fig.)    •     .     • 
Ventral  blood  vessel  of  earth- 
worm   


250 

48 

49 

225 

202 

168 

9 

136 

170 

189 

268 
268 
287 
278 

389 

275 

365 

27 

311 

317 

400 

306 
2 

268 
201 
272 
197 
371 
29 
399 
195 

197 

196 

197 
196 

82 


Ventral  nerve  chain  of  cray- 
fish    90 

Ventral  surface  of  earthworm  80 

Ventricle  (fourth)  of  brain  .     .  119 

Ventricles  of  heart     .     .     .     .  201 
Venus  mercenaria,  edible  mol- 

lusk 100 

Venus's  flytrap  (fig.)  ....  391 

rapid  movement  of       ....  392 

use  of  leaves  in 294 

Vermiform  appendix     .     .     .  168 
Vertebrates,   a  group  of   ani- 
mals    6 

discussed 103 

Vesper  sparrow,  at  hemp  and 

millet  station 148 

Vetch,  member  of  pulse  family  329 

Villi,  described .173 

Villus,  diagram  of  (fig.)    .     .     .  174 
Vines,    comparison    with    tree 

trunks     ....          ...  286 

Violet,  capsule  of  (fig.)      .      308,  310 

cleistogamous  flower  of    .     .     .  302 

example  of  irregular  flower      .  302 

fruit  of  (fig.)       .......  308 

long-spurred  (fig.)   .....  397 

plant  (fig.) 301 

Virginia  deer  (fig.)      ....  156 

fawns  of  (fig.) 156 

Virgin  forest  (fig.) 379 

Virus  in  inoculation  ....  252 

Viscera  of  clam 98 

Visceral  ganglion  of  clam      .  98 

Vitreous  humor 216 

Vocal  cords,  location  of  .     .     .  194 
Voice  box  (fig.)    ....      193,  194 

Voluntary  muscle  cells  (fig.)  188 

Voluntary  muscles     ....  188 

Volvox 55 

colonial  protozoa,  example  of  .  55 

described  (fig.) 56 

Vomiting 168 

Vorticella  (fig.) 52 

Vultures,  beneficial  birds      .     .  147 

example  of  Raptores   ....  141 

toe  of 140 

W 

Walking  sticks 20 

Walnut,  family  discussed      ,    .  327 


I  \  hi   \ 


i.; 


Walnut,  continut  d 

plant  protein  in  English  •     .     .  IT" 

tree  (fig.) 

twig  (fig.) 

Warbler,  yellow,  nest  <»f  (fig.).  142 

Warm-blooded  animals      .     .  IfiO 

Warm  milk,    moltiplicatioo  <»f 

bacteria  in 360 

Warmth.    ;i    condition    of    the 

growth  of  bacteria 34 1 

Washing    away    of    soil    by 

floods 386 

Wasp  fly,  beneficial  insert      .    .  n 

Wasps,  members  of  Bymenop- 

tera 20 

Waste  land,  after  a  fire  I  figs.  I  .  381 

Waste  materials  of  photosyn- 
thesis;        276 

Waste  products  of  IkmIv      .     .  206 

removed  by  excretion    .     .     .  2<n; 

Water,  a  necessary  condition  for 

growth  of  bacteria    ....  347 
basis  of  classifying   plants  in 

societies 393 

contains  bacteria •"•h 

composition  of 9 

habitat  of  plants 323 

sanitary  measures  forprotecting  242 

supply,  stti'lent  report  on     .     .  242 

Water  beetles,  destroyers  of 

mosquitoes 42 

Water  horehound  (fig.)       .     .  331 

Waterlilies,  air  supply  of     .     .  •".'.»» 

hydrophytes  (fig.) 

structure  of  stem  of    .     .     .     .  286 

white  (fig.) 392 

Water  snail,  host  of  liver  fluke  77 

Wax,  in  ear 218 

produced  in  U.  8.,  value  of  .  39 

Waxed    paper,     in     transpira- 
tion experiment 296 

Weasels,  destroyed  by  hawks  .  i  \'< 

harmful  animals 1 56 

Webbed    toes,    of    Bwimming 
birds i  '~ 

Weeds,  common,  lisi  of     .     .     . 

definition  of 

in  plant  succession 400 

reasons  for  success  of  . 

seeds  destroyed  by  birds .    .    .    M7 


at 


140 
148 
108 

216 


'//•■    to  i    ■ 

Weevils,  damage  to  beam 
(fig.)   •    ■ 
harmful  beetles 

Wheat,  ■  monocotyledoi 
amount  produced  i>\  i     S.   .    . 
bread,  \  aloe  of  ai  foiMi    .    .    .    ] 7 ^ 
breakfasl  food,  value  0             i     178 
cereal  (fig.) 

flour,  value  of  as  fo<  ■•!       ... 

Indehiscenl  fruit 

map  «>f  production  >>t  <  I 
member  of  grass  family   . 
one  of  first  cultivated  plant s 

•  dlings  1  iiu  ) 

Whip  grafting- Mi  _-  1  .  . 
White  blood  corpu.-rles 
White-breasted  nuth. 

u  hole  -rain  stat  iou  , 
White-crowned  sparrow 

bemp  ami  millet  stat  ion 
Whiteflsh,  example  of  a  bony 

fish 

White  grubs  eaten  by  birds 

White  of  the  eye 

White  pine,  value  of    ...     . 
White-throated     sparrow 

hemp  and  millet  station    .    .    n> 
Whole    grain    station,     bir.ls 

frequent  ing 149 

Whooping  cough,  a  bacterial 
rtifleanfi      

e\posUle    t0 

Wigglers.  larva- of  mosquito*-*      19 
Wild  plants,  Improvement  of  by 

man 

Willow,  flow  .  -"l 

Wind-distributed  frn." 
Window-growing  plant 

sponse  to  light  in     ... 
Windpipe  .... 

Wind-pollinated    I  rfl    of 

grass  Family    .    . 
characterist  ica  of 

id  pollination 
Wine,  use  of  yeast  in  making 
Wing-Wee  air  sues  of   pine 

pollen 

Wing  of  pine  seed 
Wings,  ol  birds   .... 

Is ^'' 


44 


INDEX 


References  are  to  pages 


Winter  visitants,  examples  of  141 
Wistaria,  member  of  the  pulse 

family 329 

Witch-hazel,  explosive  fruit  of  312 
Wood,  example  of  organic  mat- 
ter    10 

formation  of 290 

of  spruce  (fig.) 290 

sections  of  (fig.) 290 

Woodchucks,  young  (fig)   •     •  157 
Wooded   area,   under  govern- 
ment control 387 

Woodpeckers,  at  suet  station  148 

(downy)  permanent  residents  .  141 

food  of 27,  31 

holes  made  by  (fig.)     ....  27 

Wood-pulp,  source  of  ...     .  384 

Woody  stem,  sections  of  (fig.)  289 

structure  of 287 

use  of  elements  in 290 

Woody  twig,  buds  of  ...     .  287 

Wool,  source  of 155 

indirect  product  of  plants    .     .  401 
Woolly  aphis,  member  of  He- 

miptera  (fig.) 24,  25 

Work,  of  the  yeast  plant  .     .    .  354 

of  bean  leaf 275 

Workers  (bees) 35 

Worm,  in  the  apple  (fig.)  ...  18 

planarian  (fig.) 77 

Worm-like  animals,  classified  6 

Worm  group,  discussed  ...  76 

summary  of 84 

Worms,  classified 6 

Wort,  formation  of 355 

Wren,  a  useful  bird 145 

food  of 31 


X-ray  photograph,  of  appen- 
dix and  part  of  large  intes- 
tine (fig.)     . 169 

of  Easter  lily  (fig.)      ....  327 

of  elbow  (fig.) 185 

of  hand  of  adult  (fig.)  ....  186 

of  child  (fig.) 186 

of  human  stomach  (fig.)   .     .     .  168 

Xylem,  conductor  of  water    .     .  290 

in  fibrovascular  bundle  of  corn  280 

position  in  vascular  bundle  .     .  269 

relation  to  cambium    ....  287 


Xerophytes 


396 


Year's  growth  of  twig,  how 

told 289 

Yeast,  in  bread  making     .     . '  .    179 
plant,  described  (fig.)  .     .     .  354,  355 

enzyme  of 354 

use  of 355 

reproduction  of 3 

Yellow  fever,  carried  by  mos- 
quito   42,  239 

caused  by  protozoa  .  .  .47,  234 
Yellow  pine,  value  of  ...  .  385 
Yellow  swallowtail  (fig.)  .  .  33 
Yellow  warbler,  nest  of  (fig.)  .     142 

Yolk,  of  fish  eggs 109 

sac  on  young  fish  (fig.)  •  •  .  HI 
Youth,  a  period  of  life  ....     163 


Zeppelins,  use  of  hydrogen  gas 

for 8 

Zygospore,  advantages  of    .     .  341 

Zygote  of  spirogyra  ....  341 

Zymase,  work  of 179 


IMPORT  U8HARY 

%  C  State  CWIejfe 


